Physics Midterm – Flashcards
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free fall
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describes situations in which the only force acting on an object is the force of gravity
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when is the velocity zero in a free fall problem
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at the top of motion when it is thrown or dropped
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what direction does the acceleration point when an object is thrown upward
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always downward in free fall and projectile motion problems
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ignoring air resistance what objects are in free fall
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a dropped tennis ball, a tennis ball thrown upward, a tennis ball hit downward, a bullet fired from a gun
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when the velocity of an object in free fall has the same magnitude but the opposite direction as the initial velocity, it is the same height as it began
- true or false
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true
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what is the SI unit of displacement
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meters (m)
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what is the metric unit of acceleration
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meters per second² (m/s²)
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what is the conversion between cm and inches
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1in = 2.54cm
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how many square feet are there in a square yard
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9 ft² = 1yd²
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which of the following is not a unit of acceleration
a. km/ h sec
b. km/ hr²
c. m/ sec
d. m/ min²
e. all of these
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c. m/ sec
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what are scalars?
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time, distance, and speed
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what are vectors?
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position, velocity, acceleration, displacement
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how do you find relative velocity
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(velocity of observed object) - (velocity of the observer)
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what is meant by the reaction time of a driver
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reaction time is the time interval that passes before the brakes are applied
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what is the distance covered by a jogger who runs 4 mi east, 3 mi south, 2 mi east, and 3 mi north
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12 miles
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what is meant by "g's of acceleration"
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tells how many times the Earth's acceleration due to gravity a given acceleration is
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what is instantaneous velocity
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speed and direction of an object at a given moment in time
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which of the following accelerations would cause a car traveling 35 mi/h west slow down?
a. 15 ft/sec² east
b. 15 ft/sec² west
c. 15 ft/sec² downward
d. 0 ft/sec²
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a. 15 ft/sec² east
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what happens when velocity and acceleration are opposite in direction
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objects will slow down
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what is the displacement of a jogger who runs 4 mi east, 3 mi south, 2 mi east, and 3 mi north
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6 miles east
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0.000310 in scientific notation
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3.10 ∙ 10⁻4
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how many significant figures does 20.020 have
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five
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what is the shape of a graph that is direct proportionality
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a straight line
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what is the shape of a graph that is a quadratic relationship
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a parabola
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what is a vector
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quantity with both magnitude and direction
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what can be done to a vector and not change it
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translating
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what changes vectors
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rotating, reflecting, and dialating
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how are angles measured in vector problems
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the angle is measured counterclockwise from the x axis
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newtons first law
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Inertia, an object at rest stays at rest and an object in motion stays in motion
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newtons second law
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fnet= ma, the net force and the acceleration are directly proportional; acceleration is inversely proportional to mass
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newtons third law
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when object A exerts a force on an object B, then object B will exert an equal and opposite force on object A
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what are the 4 main types of individual forces
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applied force, frictional force, weight, normal force
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apparent weight
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refers to normal force and is how heavy one feels when an elevator is moving
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what is the net force exerted on an object
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the vector sum of all the individual forces exerted on an object as a vector
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can an object be weightless
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yes
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can an object be massless
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no
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which of these depends on location
- mass
-weight
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weight
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which direction does the net force point
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points in the same direction as acceleration
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which direction does the normal force point
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perpendicular to the surface of contact
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which direction does the frictional force point
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parallel to the surface of contact
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what is momentum
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product of an objects mass and its velocity
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what is impulse
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equal to the change in momentum
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elastic
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bouncing off each other
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inelastic
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sticking together
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what is the law conservation of momentum
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total momentum is the same as total momentum after a collision
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what is work
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occurs when a force is applied to make an object move some distance
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what is power
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rate at which work is done
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what is potential energy
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stored energy, related to position
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what is kinetic energy
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motion
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what is the law conservation of energy
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energy is neither created nor destroyed
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what is total mechanical energy
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the sum of the potential energy and kinetic energy of an object
