Physics: 1-11 – Flashcards
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Physics is the most basic Science because
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All of the above
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Which one of the following problems would not be part of Physics?
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Identifying all the bones in the human body
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Which of the following steps is not a part of the scientific method?
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Repeat the Experiments until the answers math the predictions
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A hypothesis is
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an educated guess that has yet to be proven by experiment
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A scientific fact is
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close agreement by competent observers of observations of the same phenomena.
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A theory is
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a synthesis of a large collection of information including well tested guesses.
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The difference between a hypothesis and a theory is that a hypothesis is
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an educated guess where as a theory has been tested successfully many times in many ways.
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One difference between a hypothesis and a theory is that a hypothesis
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is a guess that has not been well tested whereas a theory is a synthesis of well tested guesses
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Which of these is a scientific hypothesis
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Atoms are the smallest particles of matter that exist
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A scientific hypothesis may turn out to be right or it may turn out to be wrong. If it is a valid hypothesis there must be a test for proving that it is
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wrong
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To test a scientific hypothesis you would
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set up many experiments and look at the results
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Which of the following statements is not true?
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A good scientist is influenced by his or her likes and dislikes
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Science, art and religion do not contradict one another because
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all three have different domains
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Which of the following is a reason to express scientific findings mathematically?
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the findings become easier to verify by experiment
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Which of the following is a problem that some people blame on technology?
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widespread pollution
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A science teacher, an art instructor and a religious studies teacher are arguing about their respective disciplines. Which of the following could be a claim that each teacher makes?
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The goal of my discipline is to search for order and meaning in the world.
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A 15-N force and a 45-N force act on an object in opposite directions. What is the net force on the object
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3oN
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What is the maximum resultant possible when adding a 2-N force to and 8-N force?
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10N
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A 5-N force and a 30-N force act in the same direction on an object. What is the net force on the object ?
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35N
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What is the minimum resultant possible when adding a 5-N force to an 8-N force?
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5N
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Equilibrium occurs when
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all of the above
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A girl whose weight is 500 N hands from the middle of a bar supported by two vertical strands of rope. What is the tension in each strand?
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250N
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The weight of a person can be represented by a vector that acts
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straight down, even if the person is standing on a hill
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What would be the safest war to put up a clothesline
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with some slack in the line
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A barge is being pulled along a canal by two ropes that make equal angles with the direction in which the barge points. Assuming the two pulls on the barge are equal, in what direction does the barge move?
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Both B and C: B-It moves straight ahead C- it moves in the direction of the resultant force on it
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A clothesline os stretched between two trees. A tire hangs in the middle of the line and the two halves of the line make equal angles with the horizontal. The tension in the line is
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more than half the tires weight
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A 100-N lantern is suspended by a pair of ropes with 120 degrees between them (Each 60 degrees from the vertical). The tension in each rope is
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100N
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What is needed to describe a vector quantity?
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both magnitude and direction
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A scalar quantity has
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only magnitude
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In order to find the components of a vector, you should
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all of the above
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You are helping your aunt move a piano on wheels from one too to another. When you push the piano horizontally, it moves at a constant speed. What can you say about the piano.
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It is in dynamic equilibrium
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The basic unit used by scientist to describe length is the:
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meter
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The value for the speed of light is
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186,000 miles/sec
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An objects mass on the moon would be the same as its mass on earth.
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true
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If an object in motion is unchanged, it is said to be:
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in dynamic equilibrium
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Speed is.......
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a measure of how fast something is moving, always measured in terms of a unit of distance divided by a unit of time and the distance covered per unit time
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One possible unit of speed is
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miles per hour, light years per century and kilometers per hour
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When you look at the speedometer in a moving car, you see the car's
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instantaneous speed
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A train travels 6 meters in the first second of travel, 6 meters again during the second second of travel and 6 meters again during the third second. Its acceleration is
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0 m/s squared
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A car starts from rest and after 7 seconds it is moving at 42m/s. What is the car's average acceleration?
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6m/s squared
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As an object falls freely in a vacuum, its
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velocity increases
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In the absence of air resistance, objects fall at constant
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acceleration
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A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed of the ball when caught would be
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more than the speed it had when thrown upwards
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Suppose an object is in free fall. Each second the object falls
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a larger distance than in the second before
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If you drop a feather and a coin at the time in a tube filled with air, which will reach the bottom of the tube first?
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the coin
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Consider drops of water leaking from a water faucet. As the drops fall they
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get farther apart
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A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
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directly downward
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The hang time (time one's feet are off the ground in a jump) for most athletes is
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less than 1 second
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When a basketball player jumps to make a shot, once the feet are off the floor, the jumper's acceleration
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is g; no more, no less
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Suppose you take a trip that covers 180 km and takes 3 hours to make. Your average speed is
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60 km/h
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Suppose a car is moving in a straight line and steadily increases its speed. It moves from 35 km/h to 40 km/h the first second and from 40 km/h to 45 km/h the next second. What is the car's acceleration?
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5 km/h x s
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A ball is thrown straight up. At the top of its path its instantaneous speed is
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0 m/s
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A ball is thrown straight up. At the top of its path its acceleration is
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about 10 m/s squared
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When something falls to the ground, it accelerates. This acceleration is called the acceleration due to gravity and is symbolized by the letter g. What is the value of g on Earth's surface?
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about 10 m/s squared
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A car accelerates at 2 m/s. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 20 m/s?
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10 seconds
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If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by
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about 10 m/s
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A freely falling object starts from rest. After falling for 6 seconds, it will have a speed of about
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60 m/s
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A freely falling object starts from rest. After falling for 1 second, it will have a speed of about
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10 m/s
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If a projectile is fired straight up at a speed of 30 m/s, the total time to return to its starting point is about
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6 seconds
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The vertical height attained by a basketball player who achieves a hang time of a full one second is about
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1.2 m
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Suppose a jumper claims a hang time of 2 seconds. Then that jumper must be able to jump a vertical distance of
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5 m
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Acceleration is defined as
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the rate at which velocity changes itslef
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Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?
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to nearly its original height
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Friction is a force that always acts
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opposite to an object's motion
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The law of inertia states that an object
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will continue moving at the same velocity unless an outside force acts on it, will continue moving in a straight line unless an outside force acts on it, that is not moving will never move unless a force acts on it and at rest will remain at rest unless acted on by an outside force
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The law of inertia applies to
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both moving and nonmoving objects
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After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals
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zero, since no force is necessary to keep it moving
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A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that
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the milk carton has inertia
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An object following a straight line path at constant speed
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has zero acceleration
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Friction
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come from microscopic bumps that act as obstructions to the object's motion, is the name given to the force acting between surfaces sliding past one another, acts in a direction that opposes the motion of an object
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One object has twice as much mass as another object. The first object also has twice as much
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inertia
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Compared to its mass on Earth, the mass of a 10 kg object on the moon is
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the same
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The mass of a lamb that weighs 110 N is about
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11 kg
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How much does a 3.0 kg bag of bolts weigh?
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29.4 N
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A bag of sports equipment has a mass of 10.0 kilograms and a weight of
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98 N
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An object weighs 30 N on Earth. A second object weighs 30 N on the moon. Which has the greater mass?
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the one on the moon
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A vector is a quantity that has
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C. magnitude and direction
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A scalar is a quantity that has
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B. magnitude
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When representing velocity as a vector
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D. all of the above
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In order to find the components of a vector, you should
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D. all of the above
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Which of the following would NOT be considered a projectile?
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B. A cannonball rolling down a slope
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The horizontal component of a projectile's velocity is independent of
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C. the vertical component of its velocity
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In the absence of air friction, the vertical component of a projectile's velocity doesn't change as the projectile moves.
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A. always false
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In the absence of air friction, the horizontal component of a projectile's velocity doesn't change as the projectile moves.
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B. always true
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A the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?
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A. neither. They both hit the ground at the same time.
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A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is
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D. entirely horizontal
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In the absence of air resistance, the angle at which a thrown ball will go the farthest is
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C. 45 degrees
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A ball thrown in the air will never go as far as physics ideally would predict because
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C. air friction slows the ball
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At what part of a path foes a projectile have minimum speed?
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C. At the top of its path
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A cannonball is launched from the ground at an angle of 30 degrees above the horizontal and a speed of 30 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of
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C. 30 m/s
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A projectile launched horizontally hits the ground in 0.8 seconds. If it had been launched with a much higher speed in the same direction, it would have hit the ground (neglecting Earth's curvature and air resistance) in
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B. 0.8 s
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A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it
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D. is not acted on by any horizontal forces
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An object is dropped and falls freely to the ground with an acceleration of g. It it is thrown upward at an angle instead, its acceleration would be
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D. g downward
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A baseball is hurled into the air at an angle of 30 degrees above the horizontal and lands on a target if it is thrown at an angle of
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D. 60 degrees
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A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 60 m/s, where will the cannonball be 1 second later? (Neglect air resistance)
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C. 60m downrange
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After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)
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C. the same as when it was at the top of its path
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An airplane flying into a head wind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed it
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A. more
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Jose can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard is moving horizontally, Jose can jump
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A. no higher
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What is the resultant of a 3-unit vector and 4-unit vector at right angles to each other?
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B. 5 units
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In Chapter 4, you learned about "hang time," the time a jumper's feet are off the ground in a vertical jump. If the jumper runs horizontally and has the same vertical component of takeoff velocity, hang time will be
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A. no different
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Suppose a small plane can fly at 170 km/h relative to the surrounding air. Suppose also that there is a 60 km/h tailwind. How fast does the plane's shadow move across the ground?
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E. 230 km/h
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At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?
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A. neither- they both hit the ground at the same time
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A cannonball is fired at some angle into the air. In the first second it moves 5 meters horizontally. Assuming it doesn't hit the ground and air resistance is negligible, how far does it move horizontally in the next second?
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C. 5m
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In the absence of air resistance, at what other angle will a thrown ball go the same distance as one thrown at an angle of 75 degrees?
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A. 15 degrees
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A ball is thrown straight upward a 10 m/s. Ideally (no air resistance), the ball will return to the thrower's hand with a speed of
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C. 10 m/s
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A cannon with a barrel velocity of 140 m/s launches a cannonball horizontally from a tower. Neglecting air resistance, how far vertically will the cannonball have fallen after 4 seconds?
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A. 80m
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Accelerations are produced by
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forces
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How does acceleration of an object change in relation to its mass? it is..
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inversely proportional
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The acceleration produced by a net force on an object is...
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none of the above
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When an object reaches terminal velocity its acceleration is..
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0 m/s
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A 10-kg brick and a 1-kg book are dropped in a vacuum. the force of gravity on the 10kg brick is..
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10 times as much as the force on the 1 kg book
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When a women stands with two feet on a scale the scale reads 280 N. when she lifts one foot the scale reads...
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280 N
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Suppose the force of friction on a sliding object is 25 N. the force needed to maintain a constant velocity is..
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25N
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an apple weights 1-N. the net force on the apple when it is in free fall is..
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1 N
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A girl pulls on a 10-kg wagon with a constant force of 20 N. what is the wagon's acceleration?
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2 m/s
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ab object has a constant mass. A constant force on the object produces constant
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acceleration
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A force of 3N accelerates a mass of 3 kg at the rate of 1m/s. the acceleration of a mass of 6 kg acted upon by a force of 6 N is
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the same
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A push on a 1 kilogram brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kilogram brick one would have to push
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with 10 times as much force
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A rock is thrown vertically into the air. at the very top of its trajectory the net force on it is..
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its weight
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a box is dragged without acceleration in a straight-line path across a level surface by a force of 13 N. what is the frictional force between the box an the surface
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13 N
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the unit of pressure is
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newtons per square meter
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which of the falling would exert the most pressure on the ground?
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a women standing in high heel shoes
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a tennis ball and solid steel ball with the same diameter are dropped at the same time. which ball has the greater force acting on it?
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the steel ball
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a tennis ball and solid steel ball with the same diameter are dropped at the same time. in the absence of resistance, which ball has the greater acceleration?
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they both have the same acceleration
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if you pull horizontally on a desk with a force of 150N and the desk doesn't move, the friction force must be 150 N. now if you pull with 250 N so the desk slides at a constant velocity, the friction is
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250 N
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a block is at rest on an incline. the force of friction necessary to prevent the block from sliding increased when the incline angle is
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increased
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consider a ball rolling down the decreasing slope inside a semicircular bowl(the slope is steep at the top of the rim, get less steep towards the bottom, and is zero (no slope) at the bottom). as the ball rolls from the rim downward toward the bottom, its rate is gaining speed
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decreases
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a speeding truck locks its brakes and it skids to a stop. if the trucks total mass were doubled, its skidding distance would be
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the same
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if the force acting on a cart doubles, what happens to the carts acceleration
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it doubles
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suppose a cart is being moved by a force. if suddenly a load is dumped into the cart so that the cats mass doubles, what happens to the carts acceleration?
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it halves
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you are on a frozen pond, and the ice starts to crack. if you lie down on the ice and began to crawl......
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decreases pressure on ice
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a 20 N falling object encounters a 4 N of air resistance. the magnitude of the net force on the object is
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16 N
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a sports car has a mass of 1500 kg and accelerates at 5 meters per second squared. what is the magnitude the force acting on the sports-car?
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7500 N
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a tow truck exerts a force of 2000 N on a car, accelerating it at 1m/s. what is the mass of the car?
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2000 kg
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a jet has a mass of 40,000 kg. the thrust for each of four engines is 20,00 N. what is the jets acceleration when taking off?
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2 m/s
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you pull horizontally on a 50kg crate with a force of 450N and the friction force on the crate is 250N. the acceleration of the crate is?
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4m/s
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how much force is needed to accelerate a 4 kg physics book to an acceleration of 2. m/s
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8 N
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a jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 50,000 N. how much air resistance acts on the jet
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50,000 N
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A 6 N falling object encounters a 6 N of air resistance. the magnitude of the net force on the object is
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0 N
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if shopping cart A has five times more mass in it than shopping cart B and the two carts are pushed with equal forces, you can expect the acceleration of the shopping cart A to be
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1/5 times that of shopping cart B
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If a truck has ten times the mass of a car and the two vehicles are pushed with an equal force, you would expect the acceleration of the truck to be
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1.10 times that of the car
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An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is
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the same.
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If your car runs out of gas, why can't you push on the cars windshield from the inside to move it?
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In order for the car to move, a force must be exerted by the car on the ground.
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A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the
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road.
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Nelly Newton holds an apple in her hand. If action is Earth pulling on the apple, then reaction is
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neither A nor B
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A 60-kg person on in-line skates pushes against a wall with a force of 30 N and recoils. What acceleration does that person experience?
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0.5 m/s/s
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If a horse pulls on a wagon at rest, the wagon pulls back equally on the horse. Can the wagon be set into motion?
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Yes, Because there is a net force acting on the wagon.
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A helicopter can fly because:
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it pushes away with a force greater than the force of Earth's gravity on the helicopter.
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You drive past a farm, and you see a cow pulling a plow to till a field. You have just learned about Newton's third law, and you wonder how the cow was able to move forward if the plow is exerting equal and opposite force on the cow. Which of the following explains the movement of the cow and plow?
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The force exerted by the cow on the plow is smaller than the force that the cow exerts on the ground to move forward.
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According to Newton's third law, if you push gently on something, it will push
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gently on you.
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In order for newtons third law to occur,
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at least two objects and two forces are needed.
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As a 600-N woman sits on the floor, the floor exerts a force on her of
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600 N.
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A pair of blocks, one 2 times as massive as the other, are connected by a compressed spring. When the spring is released, the blocks fly apart. Compared to the heavier block, how many times as fast as the lighter block accelerate?
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2 times as fast
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Earth pulls on the moon, and similarly the moon pulls on Earth. This is evidence that the
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both a and b
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A rocket is able to accelerate in the vacuum of space what it fires it's engines. The force that propels the rocket is the force
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of the exhaust gases on the rocket.
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Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.
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Always true
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If you exert a force of 12,000 N on a 3000 kg car and a 6000 kg truck that are both originally at rest, what will be the resulting acceleration of the objects?
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The car will accelerate 4 m/s/s and the truck will accelerate 2/m/s/s.
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An archer shoots and arrow. Consider the action force to be the bowstring against the arrow. The reaction to this force is the
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arrow's push against the bowstring.
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Forces always occur
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in pairs.
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Bronco the skydiver falls toward Earth. The attraction of Earth on Bronco pulls him down. The reaction to this force is
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Bronco pulling up on Earth.
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A player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction to this force?
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The force of the ball against the bat
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If you push off the ground with a force of 350 N when you jump upward, what force pushes Earth downward?
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350 N
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A fighter punches a piece of paper in mid air, and brings it from rest up to a speed of 40 m/s in 0.08 seconds. What is the force of impact on the paper if the mass of the paper is 0.01 kg?
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5.0 N
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Woman weighing 550 N sits on the floor. She exerts a force on the floor of
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550 N
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A large truck and a small car traveling at the same speed have a head on collision. The vehicle to undergo the greater change in velocity will be
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the small car.
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Two people have a tug-of-war on low friction ice. One person has two times the mass of the other. Compared to the lighter person, how many times as fast as the heavier person accelerate?
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1/2 as much
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Two people pull out of rope in a tug-of-war. Each pose with 400 N of force. What is the tension in the rope?
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400 N
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A player catches a ball. Consider the action force to be the impact of the ball against the players glove. What is the reaction to this force?
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The force the glove exerts on the ball
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A person is attracted towards the center of earth by a 440 N gravitational force. The force with which Earth is attracted toward the person is
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440 N.
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As a ball falls, the action force is the pool of earths mass on the ball. What is the reaction to this force?
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The pull of the ball's mass on earth
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A high school student hits a nail with a hammer. During the collision, there is a force
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on the nail and also on the hammer.
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What engine thrust (in Newtons) is required for a rocket of mass 35 kg to leave the launching pad?
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350 N
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A karate chop delivers a blow of 2300 N to a board that breaks. The force that acts on the hand during this feat
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is 2300 N.
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Suppose two people, one having three times the mass of the other, pull on opposite sides of a 20-meter rope while on frictionless ice. After a brief time, they meet. The more massive person slides a distance of
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5 m.
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Suppose you accidentally drive into a tree. Which of the following correctly describes the interaction between your car and the tree?
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The car and the tree at mutually exert equal and opposite forces on each other.
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An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is
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larger.
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The momentum of an object is defined as the objects
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mass times its velocity
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Which has more momentum, a large truck moving at 30 miles per hour or a small truck moving 30 miles per hour
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The large truck
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Compared to a sports car moving at 30 miles per hour, the same sports car moving at 60 miles has
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twice as much momentum
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If the momentum of an object changes and its mass remains constant
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it is accelerating(or decelerating) there for is a force acting on it, its velocity is changing
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The momentum change of an object is equal to the
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impulse acting on it
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In order to increase the final momentum of a golf ball we could
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increase the force acting on it, follow through when hitting the ball, increase the time of contact with the ball, swing as hard as possible
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The reason padded dashboards are used in cars is that they
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increase the time of impact in a collision
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Momentum of a system is conserved only when
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there are no forces acting on the system
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A collision is considered elastic if
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after the collision the objects have the same shape as before the collision
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Suppose Katie is standing on a pond where there is no friction between her feet and the ice, in order to get off the ice she can
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throw something in the direction opposite to the way she wants to go
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which of the following has the largest momentum
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a pickup truck traveling down the highway
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A freight train rolls along a track with considerable momentum. If it were to roll at the same speed but had twice as much mass its momentum, would be
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quadropel
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A cannon recoils from launching a cannonball. the speed of the cannons recoil is small because the
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cannon has far more than the cannon ball
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suppose a cannon is made of a strong but very light material, suppose also that cannonball is more massive than the cannon itself. for such a system
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the target would be a safer place that where the cannon operator is located
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two objects, A and B have the same size and shape, but A is twice as heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the same time, But A has a higher
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momenutm
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In order to catch a ball, a baseball player moves his or her hand backward in the direction of the balls motion. Doing this reduces the force of impact on the players hand principally because
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the time of impact is increased
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A care traveling along the highway needs a certain amount of force exerted on it to stop. More stopping force may be required when the car has
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less stoping distance, more momentum, more mass
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A cannon fires a cannonball. the speed of the cannon ball will be the same as the speed of the recoiling cannon
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if the mass of the cannonball equals the mass of the cannon
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the force of an apple hitting the ground depends upon
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the speed of the apple just before it hits, the time of impact with the ground, whether or not the apple bounces , air resistance of the apple as it falls
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When you jump off a step, you usually bend your knees as you reach the ground. By doing this, the time of the impact is about 10 times more what it would be in a stiff legged landing, and the average force on your body is reduced by
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about 10 times
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Recoil is noticeable if you throw a heavy ball while standing on roller skates. if instead you go through the motions of throwing the ball but hold onto it, your net recoil velocity will be
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zero
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A Karate expert executes a swift blow and splits a cement block with her hand
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the forces on both the block and the experts hand have the same magnitude, the time of impact on both and the experts hand are the same the impulses on both the block and the experts hand have the same magnitude
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A moving freight car runs into an identical car at rest on the track. The cars couple together. compared to the velocity of the first car before the collision the velocity of the combined cars after the collision is
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one half as large
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two gliders having the same mass and speed move toward each other on an air track and stick together. after the collision the velocity of the gliders is
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zero
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A piece of putty moving with 2 units of momentum strikes and sticks to a heavy bowling ball that is initially at rest. after the putty sticks to the ball, both are set in motion with a combined momentum that is
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2 units
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The force that accelerates a rocket into outer space is exerted on the rocket by
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the exhausts gas
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If all people, animals, trains, and trucks all over the world began to walk or run towards the east then
answer
earth would spin a bit slower
question
Suppose an astronaut in outer space wished to toss a ball against a very massive and perfectly elastic concrete wall and catch it as it bounces back. If the ball is as massive as the astronaut then
answer
the astronaut will never catch the first bounce
question
a table tennis ball moving forward with 5 units of momentum strikes and bounces backward off a heavy bowling ball that is initially at rest and free to move . The bowling ball is set in motion with a momentum of
answer
5 units
question
Superman is at rest in space when he throws an asteroid that has more mass than he does. Which moves faster, Superman or the Asteroid?
answer
Superman
question
A cannonball shot from a long barrel cannon travels faster than one shot from a short barrel because the cannonball receives a greater
answer
Impulse
question
While roller skating Granny collides with her tiny grandson Chester who is at rest, Ignoring any friction effects, chesters speed after the collsion
answer
he and granny make a bouncing collision, each going in the opposite direction
question
A small economy car(low mass) and a Limousine(high mass) are pushed from rest across a parking lot, equal distances with equal forces. The car that receives the greater impulse is the
answer
Limousine
question
A 2-kg ball is thrown at 3 m/s what is the balls momentum
answer
6 kg ms
question
A 4 kg ball has a momenutim of 20 kg ms what is the balls speed
answer
5 ms
question
A ball is moving at 6 ms and has a momentum of 24 kg ms what is the balls mass
answer
4 kg
question
In physics, work is defined as
answer
e. force times distance
question
If you lift two loads up one story, how much work do you do compared to lifting just one load up one story?
answer
d. twice as much
question
If you lift one load up two stories, how much work do you do compared to lifting one load up only one story?
answer
d. twice as much
question
If Nellie Newton pushes an object with twice the force for twice the distance, she does
answer
c. four times the work
question
The unit of work is the
answer
c. joule
question
Power is defined as the
answer
c. work done on an object divided by the time taken to do the work
question
The unit of power is the
answer
e. watt
question
Potential energy is the energy an object has because of its
answer
c. location
question
The amount of potential energy possessed by an elevated object is equal to
answer
d. the work done in lifting it
question
Kinetic energy of an object is equal to
answer
b. one half the product of its mass times its speed squared
question
How much farther will a car traveling at 100 km/s skid than the same car traveling at 50 km/s?
answer
d. four times as far
question
An arrow in a bow has 70 J of potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it has been shot?
answer
d. 70 J
question
Energy is changed from one form to another with no net loss or gain.
answer
c. Always true
question
As a pendulum swings back and forth
answer
e. all of the above
question
When a car's speed triples, its kinetic energy
answer
d. increases by nine times
question
Rockets are launched from an airplane in the forward direction of motion. The kinetic energy of the airplane will be
answer
c. decreased
question
A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but different amounts of
answer
b. power
question
Which requires more work: lifting a 70-kg sack vertically 2 meters or lifting a 35-kg sack vertically 4 meters?
answer
c. both require the same amount of work
question
A ball is thrown into the air with 100 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is
answer
c. less than 100 J
question
An object that has kinetic energy must be
answer
c. moving
question
An object that has kinetic energy must have
answer
c. momentum
question
Which has greater kinetic energy, a car traveling at 30 km/h or a half-as-massive car traveling at 60 km/h?
answer
a. the 60 km/h car
question
A person on a roof throws one ball downward and an identical ball upward at the same speed. The ball thrown downward hit the ground with 140 J of kinetic energy. Ignoring air friction, with how much kinetic energy does the second ball hit the ground
answer
b. 140 J
question
An object at rest may have
answer
a. energy
question
If an object has kinetic energy, then it also must have
answer
c. momentum
question
If the velocity of a moving object doubles, then what else doubles?
answer
c. momentum
question
All simple machines ideally work on the principle that
answer
d. work input equals work output
question
About how efficient is a typical gasoline-burning car engine?
answer
b. 30%
question
A small economy car )low mass) and a limousine (high mass) are pushed from rest across a parking lot, equal to distances with equal forces. The car that receives more kinetic energy is the
answer
c. neither one-they receive the same amount of kinetic energy
question
A popular toy consists of an aligned row of identical elastic balls suspended by strings so they touch each other. When two balls on one end are elevated and released, they slam into the array of balls and two balls pop out the other side. If instead, one ball popped out with twice the speed, this would be a violation of the conservation of
answer
b. energy
question
Consider molecules of hydrogen gas and molecules of heavier oxygen gas that have the same kinetic energy. The molecules with the greater speed are
answer
a. hydrogen
question
How many joules of work are done on a box when a force of 25 N pushes at 3 m?
answer
e. 75 J
question
How much power is required to do 40 J of work on an object in 5 seconds?
answer
c. 8 W
question
How much work is done on a 60-N box of books that you carry horizontally across a 6-m room?
answer
a. 0 J
question
How much work is done on a 20-N crate that you lift 2 m?
answer
e. 40 J
question
How much power is expended if you lift a 60 N crate 10 meters in 1 second?
answer
e. 600 W
question
Suppose a moving car has 3000 J of kinetic energy. If the car's speed doubles, how much kinetic energy will it then have?
answer
e. 12,000 J
question
It takes 8- J to push a large box 8 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box?
answer
b. 10 N
question
If Kelly the kater's speed increases so he has three times the momentum, then his kinetic energy increases by
answer
c. nine times
question
A 60-N object moves at 1 m/s. Its kinetic energy is
answer
b. 30 J
question
Sue can easily lift a 45-N rock with the help of a lever. When she pushes down with 20 N of force, she lifts the rock 0.3 meters. How far does she move her arms to do this?
answer
b. 0.7 m
question
Mechanical energy can be in the form of
answer
c. both kinetic and potential energy
question
When a worker shovels coal into the furnace of a train engine, energy is released from the cool as heat. The heat is used to make steam, which is then used to turn the wheels of the engine. Living cells can also be thought of as machines. What biological process uses combustion to release energy from molecules so that cells can do work?
answer
b. metabolism
question
If Earth rotated faster about its axis, your weight would A. Decrease B. Increase C. Stay the same.
answer
A. Decreases
question
Stunt motorcyclist Biker Pete rides his bike inside a futuristic rotation space station- a giant rotation donut- shaped structure in space. The normal support feels like weight to him. As he rides his bike in the same direction that the station rotates, the normal force. A. Remains unaffected B. Decreases C. Increases
answer
C. Increases
question
As the rotation speed of a space habitat increases, the weight of the people inside... A. Stays the same B. Increases C. Decreases
answer
B. Increases
question
Which has greater angular speed, a horse near the outside rail of the merry go round or a horse near the inside rail? A. The outside horse B. The inside horse C. Neither- they both have the same angular speed
answer
C. Neither- they both have the same angular speed
question
Earth rotates and revolves through space. Earth rotates about the ___, which is an ___ axis. Earth revolves about the ___, which is ___ axis. A. sun, external, north/south pole, internal. B. north/south pole, external, sun, internal. C. north/south pole, internal, sun, external. D. sun, internal, north/south pole, external.
answer
C. north/south pole, internal, sun, external.
question
A race car travels in a circle with a constant speed. The net force on the race car... A. Is zero because the race car is not accelerating. B. Is directed towards the center of the curve. C. Is directed forward in the direction of travel. D. none of the above.
answer
B. Is directed towards the center of the curve.
question
Tapered rims on a railroad train wheels enable to round curves without any wheels skidding. Consider a curve with the outer track is one part in 25 linger than the inner track. The wide part of the rim should have a diameter wider than the narrow part by at least one part to____. A. 25 B. 50 C. 12.5 D. 2
answer
A. 25
question
If you whirl a ball on the end of a string and the string suddenly breaks, the ball will.... A. Fly off, tangent to its circular path. B. Fly directly toward you. C. Spiral away from your hand. D. Fly directly away from you. E. Spiral in toward your hand.
answer
A. Fly off, tangent to its circular path.
question
A person weighs less at the equator than at the poles. The reason for this has to do with the... A. Spin of the Earth. B. Influence of the sun, moon, and all of the planets. C. Tidal bulges. D. Higher temperatures at the equator, and the expansion of matter. E. Too much thanksgiving dinner.
answer
A. Spin of the earth.
question
Newbs Newton swings a rock into a circular path while holding an attached string overhead. The string makes a 45- degree angle to the vertical (compromising a "concial pendulum"). The centripetal force that holds the rock in its circular path is the.... A. Tension in the string. B. Vertical component of the string tension. C. Horizontal component of the String tension. D. None of the above.
answer
C. Horizontal component of the String tension.
question
Earth Rotates in a/ an_________direction. A. Elliptical B. Circular vector C. Clockwise D. Counter Clockwise
answer
D. Counter Clockwise
question
When a railroad train rounds a banked track, the centripetal force needed comes not from friction, but from the... A. Horizontal component of the normal force. B. Normal force. C. Vertical component of the normal force. D. None of the above.
answer
A. Horizontal component of normal force.
question
A space habitat is designed so that the variation in g between a person's head and feet is less than 0.01 g. If the person is 2 m tall, then the radius of the habitat is... A. 2000 m B. 200 m C. 20 m D. more than 2000 m
answer
B. 200 m
question
A vertical pole standing against a wall topples to the ground and the center of the pole has a speed of 26 m/s as it hits the ground. With what speed does the far end of the pole hit the ground? A. 52 m/s B. 26 m/s C. 39 m/s D. 13 m/s
answer
A. 52 m/s
question
To weigh less in the Southern Hemisphere, you should go... A. West B. North C. East D. South
answer
B. North
question
Nick Spacewalker hovers in space beside a rotating space station in outer space. Both he and the center of mass of the space station are at relative rest. If the space station is in Earth's orbit, than Nick A. may or may not be in Earth orbit. B. is not in Earth's orbit. C. Is also in Earth's orbit.
answer
C. Is also in Earth's orbit.
question
A game room in a rotating space habitat is located in a 0.25-g region. If a person can jump 0.5-m high in a 1-g region, how high can the same person jump in the game room? A. 8 m B. 4 m C. 2 m D. More than 8 m E. 0.5 m
answer
C. 2 m
question
Which of the following is not a unit of rotational speed? A. Miles per hour B. Revolutions per minute C. Rotations per minute D. Rotations per second E. Revolutions per second
answer
A. Miles Per Hour
question
The tangential speed of the outer rim of a ferris wheel is 30 m/s. What is the tangential speed of a position half- way from the center to the outer rim. A. 20 m/s B. 60 m/s C. 15 m/s D. 10 m/s
answer
C. 15 m/s
question
People in the future may well live inside a rotating space structure that is more than 2 km in diameter. Inside the structure, people on the inside of the outer edge will experience 1 g while people halfway to the axis will experience A. 1 g B. 0 g C. 1/4 g D. 2 g E. 1/2 g
answer
E. 1/2 g
question
A rock whirled on the end of a string moves in a circle because... A. Once the rock starts moving, that is its natural tendency. B. The rock continually pulls on the string. C. There is an inward force acting on the rock. D. There is a force on the rock pulling it outward. E. All of the above.
answer
C. There is an inward force acting on the rock.
question
A possible space habitat of the future is a cylinder in space rotating about its long axis. What is the relative gravitational field along the axis of the habitat? A. Three- Quarters G B. Zero C. One- Quarter G D. One- Half G E. G
answer
B. Zero
question
"Centrifugal forces" are an apparent reality to observers in a reference frame that is ... A. At rest B. An intertial reference frame C. Moving at a constant velocity D. Rotating E. Bouncing
answer
D. Rotating
question
You sit at the outer rim of a ferris wheel that rotates at 22 revolutions per minute (RPM). What would your rotational speed be if you were instead clinging to a position half- way from the center to the outer rim? A. 11 RPM'S B. 2 RPM'S C. 44 RPM's D. 22 RPM's
answer
D. 22 RPM'S
question
What is the direction of the force that acs on clothes in the spin cycle of a washing machine? A. Up B. Down C. Outward D. Inward
answer
D. Inward
question
Which has greater linear speed, a horse near the outside rail of a merry go round or a horse near the inside rail? A.The outside horse B. Neither- they both have the same speed C. The inside horse
answer
A. The outside horse
question
Stunt motorcyclist Biker Harry rides his bike inside a futuristic rotating space station- a giant rotating donut- shaped structure in space. The normal support force feels like weight to him. As he rides his bike in the opposite direction to the station's rotation, the normal force... A. Increases B. Decreases C. Remains the same
answer
B. Decreases
question
The centripetal force exerted on stunt motorcyclist Biker Bruno while riding on the inner vertical surface of a circular track is A. His weight B. The normal force C. Friction D. None of the above
answer
B. The normal force
question
At the outer edge of a rotating habitat, 130m from its center, the rotational acceleration is g. What is the rotational acceleration at a distance of 65 m from the center of the habitat. A. 2x g B. 1/3 g C. 4x g D. 1/2 g
answer
D. 1/2 g
question
A worm rests on the bottom of a tin can that is being whirled horizontally on the end of a string. Since the worm, like the tin can, moves in a circle, there must be a force on it. What exerts this force? A. Gravity B. Your hand C. The tin can D. The String E. There is no force acting on it.
answer
C. The tin can
question
Where is the center of gravity of a softball bat located?
answer
In the more massive end
question
When a wrench is slid spinning over a frictionless tabletop, its center of gravity follows
answer
a regular straight-line path
question
An object will fall over if its center of gravity is
answer
not over its area of support
question
When you carry a heavy load with one arm, why do you tend to hold your free arm away from your body?
answer
to change the center of gravity of your body and the load
question
If an object is in unstable equilibrium, any displacement will
answer
lower its center of gravity
question
If an object is in stable equilibrium, any displacement will
answer
raise its center of gravity
question
If an object is in neutral equilibrium, any displacement will
answer
neither raise nor lower its center of gravity
question
If you try to touch your toes while standing flat against a wall, you probably will fall over. The reason this happens is that
answer
your center of gravity is not located directly above your support area
question
The center of mass of the solar system
answer
varies as the planets move
question
The long heavy tail of a spider monkey enables the monkey to easily vary is
answer
center of gravity
question
The center of mass of a human body is located at a point
answer
that changes as a person bends over
question
An object thrown into the air with a spin rotates about its
answer
center of gravity
question
A fish suspended in water is in what kind of equilibrium
answer
neutral
question
A ball resting on the floor is in what kind of equilibrium
answer
neutral
question
A picture hangs on a wall from a wire that is passed over a supporting nail. The picture is in stable equilibrium because
answer
all of the above
question
Based on stability concepts, you would expect a very broad tree to have
answer
a very broad root system
question
You push a table tennis ball beneath the surface of water in a glass of water. The center of gravity of the glass of water
answer
rises
question
Torque is defined as
answer
force times lever arm
question
Suppose you try loosening a nut with a wrench, and the nut doesn't give at all. You increase your chance of success if you
answer
all of the above
question
To turn a stubborn screw, it is best to use a screwdriver that has a
answer
wide handle
question
At the health spa, Felix Flex finds that pulleys in the exercise machines are not circular, but are cams- oval-shaped pulleys. At different orientations, the cams provide different
answer
both A and B (lengths of lever arms and forces required to produce a given torque)
question
Two people sit on a balanced seesaw. When one person leans toward the center of the seesaw, that person's end of the seesaw will
answer
rise
question
A meter stick is balanced at the 50.0 cm mark. You tie a 10.0N weight at the 15.0 cm mark. Where should a 30.0 N weight be placed so the meter stick will again be balanced?
answer
61.7 cm mark
question
An object in motion with a constant force and no resistance will either travel in a straight line or travel
answer
in a circle
question
Most females have a better ability to balance their bodies in motion compared to a male because
answer
most females center of mass creates a rotational equilibrium
