question

The distance a freely falling object falls from rest in three seconds here on earth is

answer

45 m. d = 1/2a(t^2)

question

The first estimate of the size of the Moon and the first written record for the Sun-centered cosmos are attributed to

answer

Aristarchus.

question

What is the significance of the famous Apple Story that is associated with Isaac Newton?

answer

It was Newton's genius to connect the physics that explains why the apples falls under the force of gravity is the same physics that explains why the moon orbits or why the international space station orbits the earth-- it is in free fall.

question

Nellie pulls with a force of 20 N on a horizontal rope tied to a tree at rest. The net force on the rope is

answer

zero and rope tension is 20 N. (net force is zero because the tree pulls with a force of 20 N also)

question

If air resistance is neglected, a stone dropped from the roof of a single story building to the surface of the earth

answer

speeds up because of an almost constant force of gravity acting upon it.

question

Your physics teacher fired a steel ball with a velocity of 3 m/s in the horizontal direction. At the same time she dropped a similar steel ball from the same height. Which on hit the ground first and why? Neglect air resistance.

answer

They both hit the ground at the same time as the force of gravity is the same for both and only acts in the vertical direction.

question

A kilogram is a measure of an object's

answer

mass.

question

When you flick a card from beneath a coin that hardly moves, you're illustrating

answer

inertia.

question

Whenever the net force on an object is zero, it's acceleration is

answer

zero.

question

The Greek mathematician Eratosthenes made observations of sunlight striking water in the bottom of a well and shadows casting in a neighboring town to find the size of

answer

Earth.

question

A motorboat that normally travels 40 km/h in still water heads directly across a 30 km/h flowing river. The resulting speed of the boat is about

answer

50 km/h. (using the Pythagorean Theorem, 40^2 + 30^2 = 2500. Taking the square root of 2500 gives us 50)

question

The force that propels a cannonball when fired from a cannon is

answer

equal and opposite to the force the ball exerts on the cannon.

question

When a cannon is fired from a cannon, which undergoes the greater acceleration?

answer

The cannonball

question

You toss a ball upward with an initial velocity of 30 m/s. Neglecting air resistance, after 3 seconds you find that

answer

the velocity is zero and the acceleration is 10 m/s/s downward.

question

Which of the following is NOT a characteristic of a scientific hypothesis? A) there must be a doable test for wrongness B) once proved correctly by one experiment, it can never be proven wrong by any experiment C) it is only presumed to be factual after supported by experiment D) it is an educated guess

answer

B) once proved correctly by one experiment, it can never be proven wrong by any experiment

question

An 800 N man stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

answer

400 N.

question

Galileo discovered that when air resistance can be neglected, all objects fall with the same

answer

acceleration due to gravity

question

The weight of a full jug of water (like a Smartwater bottle) on the surface of the moon is

answer

less than it is here on the surface of Earth.

question

A ball starting from rest at the top of an inclined plane accelerates at 4 m/s/s and reaches the bottom of the plane in 6 seconds. What is the length of the plane?

answer

72 m. d = 1/2a(t^2)

question

What is an example of Aristotelian thinking?

answer

Heavy objects are hard to move and come to rest quickly. Earth is so heavy it does not move and is consequently stationary at the center of the cosmos.

question

Galileo taught us that if you roll a ball along a level surface it will

answer

keep rolling if friction is absence.

question

You toss a ball and it makes a curved path. At the instant that the ball leaves your hand it has a velocity which gas a horizontal component of 40 m/s and a vertical component of 20 m/s. How far from you does the ball land? Neglect air resistance.

answer

160 m.

question

Suzie Skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration

answer

decreases.

question

If a freely falling object were equipped with a speedometer on a planet where the acceleration due to gravity is 60 m/s/s, then its speed reading would increase each second by

answer

60 m/s.

question

The time it takes a car to attain a speed of 100 m/s when accelerating from rest at 5 m/s/s is

answer

20 s. V(final) = V(initial)+ at 100 m/s = (0 m/s) + (5 m/s/s)t t = (100 m/s) / (5 m/s/s)

question

Two metal balls are the same size but one weighs twice as much as the other. The balls are dropped from the roof of a single story building at the same instant of time. Neglect air resistance. The time it takes the balls to reach the ground below will be

answer

about the same for both balls.

question

Consider a rocket set to launch on a launch pad. When a rocket forces exhaust gases downward, the exhaust gases

answer

exert an upward force on the rocket.

question

A 2 kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is

answer

5 m/s/s. F(net) = ma 20 N -10 N = (2 kg)a a = 10/N / 2 kg

question

A woman exerts a constant horizontal force on a large box. As a result, the box moves across a horizontal floor at a constant speed of v0. The constant horizontal force applied by the woman

answer

has the same magnitude as the total force which resists the motion of the box.

question

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

answer

directed downward.

question

A 3 kg mass at the Earth's surface weighs

answer

30 N.

question

An object's weight is properly expressed in units of

answer

newton's.

question

A watermelon falls off a truck that is moving at 60 mph. Neglecting air resistance, the horizontal speed of the melon just before it hits the ground is

answer

about 60 mph.

question

A river 50 m wide flows due south at 1 m/s. A boat that travels 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat reaches the east bank

answer

50 m farther south.

question

A skydiver jumps from a plane and deploys a parachute. When the skydiver reaches terminal velocity, the magnitude of the forces that is the weight of the skydiver

answer

is equal in magnitude to the forces of the air drag but in the opposite direction.

question

In Physics we seek

answer

to describe nature and understand its rules.

question

A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to the state of zero acceleration first?

answer

The light woman

question

A wheel rotates with an angular speed of 6 radians per second and it has a radius of 2 meters. What is the linear speed of a bug located on the outer radius of this wheel?

answer

12 m/s v = rw

question

A seesaw is balanced with the fulcrum at its midpoint. If a 3 kg weight is placed one meter from the fulcrum on one side, where would you need to place a 6 kg weight on the opposite side in order to balance the seesaw again?

answer

One half meter from the fulcrum.

question

A cannon recoils while firing a cannonball. The speed of the cannon's recoil is relatively small because the

answer

cannon has much more mass than the cannonball.

question

A simple machine like a pulley may do all of the following EXCEPT: A) create energy B) change the direction of forces exerted C) can reuce the amount of force required to lift an object D) transform energy from one kind to another

answer

A) create energy

question

As a huge rotating cloud of particles in space gravitate together forming an increasingly dense ball, it shrinks in size and

answer

rotates faster.

question

Whether a truck come to a stop by crashing into a haystack or a brick wall, the impulse is

answer

both the same.

question

A 6 W LED produces the same amount of light as a 60 W incandescent light bulb. If both are left on for one day we find that

answer

the LED uses one tenth the energy as compared to the incandescent bulb and produces the same light because it is more efficient.

question

Compared with falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the

answer

stopping time is longer on the carpet.

question

The power required to exert a 5 N force over 4 meters in 2 seconds is

answer

10 W Power = work/time

question

The momentum of a system will remain unchanged

answer

only if you choose the system so that there are no external forces acting on it. All action/reaction forces are acting on objects inside the system.

question

If several balls are thrown straight up with different initial speeds, the quantity that will have the same value along their paths is their

answer

acceleration.

question

Centrifugal forces are

answer

apparent forces caused by inertia that feels like a radially outward force.

question

Which of the following are considered greenhouse gases? A) molecular oxygen/nitrogen B) atomic hydrogen/helium C) carbon dioxide and water vapor D) argon and neon

answer

C) carbon dioxide and water vapor

question

A light aluminum ball and a heavy lead ball of the same size roll down an incline. When they are halfway down the incline, they heavy lead ball will have greater

answer

kinetic energies, inertias, potential energies, and momentum

question

A round stone of mass 2 kg is dropped off a bridge over a river and falls for 2 seconds before reaching the water. Its momentum upon hitting the water is

answer

40 kg m/s p=mv = (2 kg)(10m/s/s * 2s)

question

An impulse can be increased by

answer

increasing the force and/or increasing the time interval.

question

Two identical space crafts move at different speeds. The faster craft has four times the speed and therefore has

answer

sixteen times the kinetic energy. KE = 1/2m(v^2) = 1/2m(4v^2) = 1/2m16(v^2)

question

A force acts on an object for a period of time and sets it in motion. Which of the following is TRUE? The force multiplied by the time is ________ and the force multiplied by the distance is ________

answer

the impulse or change in momentum, the work done by the force

question

No work is done by gravity on a bowling ball that rolls along a bowling alley because

answer

the force on the ball is at a right angle to the ball's motion.

question

Two object have the same mass and radius. One is a hoop and the other is a solid cylinder. If you race the 2 objects down an incline, neglecting air resistance, which do you expect to reach the bottom of the incline first?

answer

The solid cylinder because it has a lower rotational inertia and so it will have the greater acceleration.

question

The mass of a big fish is four times that a little fish. The speed of the little fish is 5 km/hr and the big fish is at rest. If the little fish swims into the mouth of the big fish, what is the speed of the big fish after his fish dinner?

answer

1 km/hr (net mv)before = (net mv)after 1 kg * 5 km/hr = 5 kg * v

question

What does it mean for a gas to be a green house gas?

answer

The gas is in the atmosphere and it strongly absorbs infrared radiation.

question

The mass of a ball moving at 12 m/s with a momentum of 48 kg m/s is

answer

4 kg p=mv 48 kg m/s = 12 m/s * m m= 48 kg m/s / 12 m/s

question

An apple falls from a tree from a height of 3 meters. The weight of the apple is 1 N . What is the kinetic energy of the apple just before it hits the ground?

answer

3 J KE = F(net) * d KE = 1 N * 3 m

question

In considering the work energy theorem, when negative net work is done on an object, we find

answer

the object slows down.

question

Rotational Inertia depends upon

answer

the mass of the object and the distribution of the mass about the axis of rotation.

question

An apple has a weight of 1 N at the surface of the Earth. What is the weight of the apple if it was not at the surface, but rather at one earth radii above the surface?

answer

1/4 N

question

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is

answer

greater with the brick force.

question

When a vertically falling firecracker bursts, the vector sum of momentum fragments

answer

in the vertical direction equals the momentum of the firecracker before bursting and in the horizontal direction cancels to zero.

question

A blue railroad car of mass m rolls at a certain speed and makes a perfectly inelastic collision with an orange car that has twice the mass and is at rest. After the collision, what is the speed of the coupled cars?

answer

One third the speed of the blue car before collision.

question

The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is

answer

above a place of support.

question

If you triple your speed, how does that change your stopping distance if all other conditions remain the same? Do not consider reaction time.

answer

The stopping distance is 9 times as long.

question

In considering the work-energy theorem, the work done on an object by a net force is always

answer

equal to the objects change in kinetic energy.

question

Two billiards balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?

answer

Zero

question

If you exert a net torque on an object, you will find that

answer

the object may speed up or slow down it's rotation rate.

question

The unit kilowatt-hour is a unit of

answer

energy.

question

What is the physics behind the greenhouse effect?

answer

The Sun warms the ground which causes the ground to radiate in infra-red wavelengths that are strongly absorbed by carbon dioxide and other green house gases, causing the lower atmosphere to warm.

question

A same-sized iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater

answer

momentum.

question

Which of the following requires the most mechanical work? Lifting a (10 kg, 0.1 kg, 2 kg) sack a vertical distance of (1m, 50m, 2m).

answer

Lifting a 10 kg sack a vertical distance of 1 m.

question

When an object is partly or wholly immersed in a liquid, it is buoyed up

answer

by a force equal to the weight of liquid displaced.

question

Compared to the atoms that make up the body of an elderly person, the atoms that make up the body of a newborn baby are

answer

the same age.

question

As a balloon rise higher and higher into the atmosphere its

answer

volume increases.

question

Compared to a bar of pure gold, the density of a pure gold ring is

answer

the same.

question

A spring is stretched 20 cm by a suspended 1 kg block. If two such springs side-by-side are used to suspend the 1-kg block, each spring will then stretch

answer

10cm.

question

Why can we not use powerful optical microscopes using visible wavelengths to see individual atoms?

answer

Atoms are much smaller than the wavelength of visible light.

question

What is Browian Motion?

answer

Jiggling of dust particles in a liquid caused by unseen atoms interpreted as evidence for existence of atoms.

question

Where do naturally occurring elements heavier than boron come from?

answer

They are made by stars in nuclear fusion and supernova events.

question

A block of wood that weighs 25 N is floating in a pond. Knowing this we also know

answer

The weight of the water displaced by the floating block of wood is also 25 N.

question

Why do we say that a blob of putty is inelastic?

answer

When deformed, it does not return to its original shape.

question

If an astronaut landed on a planet composed of antimatter, there would be an explosion and the

answer

astronaut and an equal amount of planet antimatter would both annihilate.

question

If you have an unidentified atom, how do you tell which element the atom is? To identify the element that an atom is, count its number of

answer

protons.

question

What is the magnitude of the Earth's gravitational force on a 3 kg rock at Earth's surface?

answer

30 N

question

How does the arrangement of atoms in a crystalline substance differ from the arrangement in a noncrystalline (amorphous) substance.

answer

Atoms in crystals are in an ordered array with long range order. In amorphous materials, they have only short range order. In amorphous materials, they are randomly distributed.

question

In Einstein's Theory of Gravitation, we understand the gravitational field

answer

as a warping of space-time by a massive object.

question

According to Newton, when the distance between two interacting objects triples (distance is multiplied by 3), the gravitational force is

answer

one ninth as much.

question

The density of a 5-cubic meter block of mass 1000 kg is

answer

200 kg/m/m/m d=m/v

question

An isotope is simply an atom that

answer

has different numbers of neutrons for the same element.

question

Which of these has the greatest number of protons in its nucleus? A) aluminum B) copper C) carbon D) gold

answer

Gold

question

A solid block of copper is mostly empty space because the atoms in the block are

answer

mostly empty space themselves.

question

Compared to the density of water, the density of a stationary fish in the middle of a pond is

answer

the same.

question

In regards to atoms that make up ordinary matter, which of the following is not true? A) the lightest and most abundant atom is hydrogen B) atoms of an element can have different numbers of electrons C) atoms are in perpetual motion D) we know of more than 1000 distinct elements that make up ordinary matter

answer

D) we know of more than 1000 distinct elements that make up ordinary matter

question

An object has the shape of a cube and is fully submersed in water. If the direction of gravity is downward, then best explanation of why the buoyant force acts upward on the submersed cube is because

answer

the water pressure against the bottom of the cube is greater than the water pressure against its top.

question

The strength of a rope depends on its

answer

cross-sectional area (thickness)

question

One thing that Tidal friction is causing

answer

is the Earth to slow its rotational rate very, very gradually.

question

The discovery of the Higgs boson will likely

answer

change our idea of what it means for matter to have mass.

question

Although solid matter is mostly empty space, we don't fall through the floor because of

answer

electrical forces.

question

A creature that is scaled up in size, keeping its proportions,

answer

will be weaker relative to its greater weight.

question

One side of the Moon continually facing Earth is

answer

a tidal lock.

question

Surface tension of water is not responsible

answer

for buoyancy.

question

When holes are drilled through the wall of a water tower, water will spurt out the greatest horizontal exit speed from the hole closest to

answer

the bottom of the tower.

question

What is true about drinking water from a straw?

answer

Air pressure pushes water up the straw, so straws can only be at most 10.3 m in height.

question

When the curve of a vertical structure matches the inverted image of a drooping chain held at both ends,

answer

the curve is called a catenary.

question

As a fluid gains speed, its internal pressure

answer

decreases.

question

The air of the atmosphere is best describes as

answer

a mixture.

question

The mass of matter is due mostly to

answer

its nucleons (protons and neutrons)

question

The cosmos is comprised mostly of

answer

Dark Energy

question

What is the event horizon of a black hole?

answer

Boundary where the forces of gravity about a collapsed star are so great that light cannot escape.

question

A mass is attached to a spring and the spring is set into simple harmonic oscillation. Where is the speed of the mass greatest?

answer

At the equilibrium point where the mass hangs when not in oscillation.

question

Hooke's Law

answer

is a principle of physics that states that the force needed to extend or compress a spring by some distance is proportional to the stress applied to it.

question

Boyle's Law

answer

pressure and volume of a gas enclosed in a space are inversely proportional.

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