Module 6: Energy

To push with 1 Newton of force across 1 meter in 1 second requires a power of... a) 1 W b) 3 W c) 1/3 W d) 2 W

a) 1 W

How many joules of energy are in one kilowatt-hour? In two kilowatt0 hours is energy. In units of joules, how much? a) 7.2 million joules b) 120,000 joules c) 1 joule d) 120 joules

a) 7.2 million joules

A beam is being driven into the ground by a pile driver. How far the beam gets pushed into the ground with each stripe will depend upon... a) any of these choices b) the kinetic energy of the pile driver weight when it first contacted the beam c) the original potential energy of the pile driver weight d) the original height of the pile driver weight

a) any of these choices

A workman can lift a barrel 1 meter vertically or roll the barrel up a 2 meter ramp to the same height. Using the ramp, the force needed is about... a) half as much b) the same c) twice as much d) four times as much

a) half as much

As the velocity of a moving ball doubles, there is also a doubling of... a) momentum b) acceleration c) all of these d) kinetic energy

a) momentum

A car jack, much like an inclined plane, can increase energy... a) never ever b) which is why its so effective c) when friction is minimized

a) never ever

Having kinetic energy, a ball must also have... a) acceleration b) impulse c) momentum d) force e) all of these

c) momentum

In deep space, two identical sticky globs of taffy are heading directly toward each other, one at 2 m/s and the other at 1 m/s. After their head-on collision, their combined speed is... a) 0.5 m/s b) 1.0 m/s c) 0.33 m/s d) 0.67 m/s

a) 0.5 m/s

Cranking out 100 watts for every 1000 watts of power received, a machine's efficiency is... a) 10% b) 90% c) 50 % d) 110 %

a) 10%

Depressing the input piston of a hydraulic press by 20 centimeters lifts the output piston by 1 centimeter. Thus, inputting a force of 1 N can raise a load with a maximum weight of... a) 20 N b) 1 N c) 15 N d) 10 N

a) 20 N

Stepping off a board 10 meters above a swimming pool, a 500 N diver falls into a pool with a kinetic energy of... a) 5000 J b) 500 J c) 510 J d) more than 5000 J e) 10 J

a) 5000 J

From rest and a height of H, a cannon ball of mass M falls to the ground. Its kinetic energy upon hitting the ground... a) is proportional to H b) all of these c) does not depend on M d) is one half its original potential energy

a) is proportional to H

The most important property determining an object's potential energy is its... a) location b) speed c) momentum d) acceleration

a) location

A rifle recoils from firing a bullet, which then has greater kinetic energy than the rifle because the force on the bullet was acting over a... a) longer distance b) longer time and a greater distance c) longer time

a) longer distance

A bowling ball at rest is set into motion upon being hit head-on by a flying golf ball, which bounces backward. Compare the momenta and kinetic energies of the two balls after the collision. The bowling ball has... a) more momentum, but less kinetic energy b) not enough information is given to say c) less momentum and less kinetic energy d) more kinetic energy, but less momentum e) more momentum and more kinetic energy

a) more momentum, but less kinetic energy

A golf ball and a ping pong ball have the same kinetic energy as they move in the same direction. The ping pong balls speed must be... a) more than the golf ball b) less than the golf ball c) the same as the golf ball d) impossible to predict without additional information

a) more than the golf ball

As it rolls down an inclined plane, a marble has its least speed... a) near the top of the incline b) impossible to predict without knowing the marbles mass c) impossible to predict without knowing the marbles exact size d) half way down the incline e) at the end the incline

a) near the top of the incline

When at rest, an object can also have... a) potential energy b) kinetic energy c) momentum d) speed e) velocity

a) potential energy

Having rolled half way down an inclined plane, a bowling ball's kinetic energy is... a) the same as its potential energy b) less than its potential energy c) greater than its potential energy d) impossible to determine

a) the same as its potential energy

Performing an amount of work in one third the time requires a power output of... a) three times the usual power output b) one third the usual power output c) the usual power output d) more information is needed

a) three times the usual power output

Consider the work required to lift one end of a heavy iron pipe to a height of 1 meter. Lifting a second identical pipe instead from its middle but to the same height requires about... a) twice as much work b) more than twice as much work c) the same amount of work

a) twice as much work

When pushing an object two times the distance while exerting a force that is the same, you do... a) twice as much work b) half as much work c) the same amount of work d) four times as much work

a) twice as much work

A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that is... a) less than 40 J b) 40 J c) more than 40 J

b) 40 J

A post is driven 0.2 meters into the ground by a 5000 N weight falling 20 meters before contact creating a force of impact (on average) of... a) 5000 N b) 500,000 N c) 5,000,000 N d) 50,000 N

b) 500,000 N

Within a vacuum, a feather and a nail descent with the same... a) forces b) accelerations c) momenta d) none of these e) kinetic energies

b) accelerations

A rolling ball has... a) speed b) all of these c) momentum d) energy e) velocity

b) all of these

Can a car jack multiply the input of force? a) sometimes true b) always false c) sometimes false d) always true

b) always true

A rifle recoils as a bullet is fired with equal... a) both of these b) but opposite amounts of momentum c) amounts of kinetic energy d) neither of these

b) but opposite amounts of momentum

Bullets are fired forward from an old WWI airplane. The airplane's momentum is thus... a) increased b) decreased c) unchanged

b) decreased

When bullets are fired from an airplane in the forward direction, the momentum of the airplane will be... a) increased b) decreased c) unchanged

b) decreased

A train carrying hundreds of open and empty hot tubs rolls horizontally with friction in a heavy rain. As water collects in the tubs, the trains speed... a) increases b) decreases c) doesn't change d) cannot be determined with the information given

b) decreases

A rolling ball at 3 m/s, two billiard balls collide head on and then bounce away from each other at 6 m/s. However this violates the conservation of... a) both momentum and energy b) energy c) no known physical law d) momentum

b) energy

In skidding to a stop, a truck moving two times as fast as an identical truck skid... a) twice as far b) four times as far c) depends on the mass of the cars

b) four times as far

A rock is thrown straight upward with 200 joules of kinetic energy. Considering air resistance, by the time it falls back to the level at which it was thrown its kinetic energy is... a) more than 200 J b) less than 200 J c) 200 J d) more information is needed

b) less than 200 J

Off the edge of a rooftop, a woman releases a rock, which hits the ground with 200 joules of kinetic energy. If she instead tosses the rock straight upward, it would eventually hit the ground with how much kinetic energy? (Ignore air resistance) a) less than 100 J b) more than 200 J c) 200 J

b) more than 200 J

To have kinetic energy, an object must be... a) at rest b) moving c) falling d) at an elevated position

b) moving

When pushing against the wall of a brick for 30 minutes or 60 minutes... a) twice as much work is done during the 30 minutes b) no work on the wall is done in either case c) it is impossible to determine how much work is done d) half as much work is done during the 30 minutes

b) no work on the wall is done in either case

To slow a car down, the cars brakes must work. Consider slowing down from 100 km/h to 70 km/h and compare that to slowing down from 70 km/h to a stop. For the brakes, which requires more work? a) slowing down from 70 km/h to a stop b) slowing down from 100 km/h to 70 km/h c) more information is needed d) equal amounts for either

b) slowing down from 100 km/h to 70 km/h

An arrow shot with double the kinetic energy of another identical arrow will penetrate into the same bale of hay... a) more than four times as deep b) twice as deep c) to the same depth d) four times as deep

b) twice as deep

A box raised 10 meters receives 200 joules of potential energy. If lifted 20 meters, the potential energy gain is... a) four times as much b) twice as much c) the same d) more than four times as much e) half as much

b) twice as much

An object lifted 10 meters gains 200 J of potential energy. If the same object is lifted 20 meters, its potential energy gain is... a) four times as much b) twice as much c) more than four times as much d) half as much e) the same

b) twice as much

A 2000 kg truck and a 4000 kg truck are lifted the same distance, but lifting the heavier truck requires... a) less work b) twice as much work c) just as much work d) four times as much work e) more than four times as much work

b) twice as much work

For a task requiring two times the time and two times the work, the power needed is... a) sixteen times as much b) unchanged c) twice as much d) four times as much

b) unchanged

Pushing a 100 kg sofa 4 meters across a carpet requires 40 joules. What was the force of the push acting on the sofa? a) 40 N b) 4 N c) 10 n d) 400 N e) 160 N

c) 10 N

With the brakes locked, a truck traveling at 50 km/hr skids to a stop in 20 meters. If it had been moving at 150 km/hr, the skid distance would have been about... a) 120 m b) 20 m c) 180 m d) 90 m e) 60 m

c) 180 m

Drawing a bow so that it has 40 joules of potential energy means that an arrow fired from this bow ideally will have akinetic energy that's... a) less than 40 J b) more than 40 J c) 40 J d) impossible to predict without additional information

c) 40 J

How much work is required to push a 15 kg chair with a force of 20 N over a distance of 2 meters? a) 600 J b) 30 J c) 40 J d) 300 J e) 3 J

c) 40 J

On a straight and level track with no friction, a 5000 kg freight car moving westward at 1 m/s collides head-on and couples with an identical 5000 kg freight car moving eastward at 2 m/s. Together they roll with a combined momentum of... a) 15,000 kg m/s b) zero c) 5000 kg m/s d) 10,000 kg m/s

c) 5000 kg m/s

While traveling down a highway, a car's engine works against a resistance force averaging 500 Newtons. The energy to do this comes from the gasoline, how many kilometers can the car travel assuming it works with 100 percent efficiency? a) 60 kilometers b) not enough information c) 80 kilometers d) more than 100 kilometers e) 100 kilometers

c) 80 kilometers

Running your car with the headlights turned on causes more fuel to be consumed. Is this true? a) this is true only if the car also moving b) no. this is always false c) this is always true d) this is true only if the car is not moving

c) This is always true

A bullet is fired from a rifle that recoils backward. After the bullet is shot outward, compared to the rifle it has... a) a smaller speed b) all of these c) a greater kinetic energy d) a greater momentum

c) a greater kinetic energy

In a vacuum, a light and heavy ball dropped from the same height will have the same... a) kinetic energies b) momenta c) accelerations d) weights

c) accelerations

Impulse concerns force and time, while work concerns the... a) acceleration that a force produces b) time and distance that a force acts c) distance that a force acts d) the change in momentum

c) distance that a force acts

On a straight and level track, a freight car moving westward at 1 m/s collides head-on and couples with an identical second freight car moving eastward at 2 m/s. Together they roll... a) westward b) neither of these. they stop c) eastward

c) eastward

A truck moves at 30 km/hr while another truck of half the mass moves at 60 km/hr. The one with greater kinetic energy is the... a) more information is needed about the distance traveled b) both have the same kinetic energy c) faster moving truck d) slower moving truck

c) faster moving truck

Gravity performs no work on a 5 kg bowling ball rolling down a bowling lane because... a) the ball's kinetic energy remains constant b) the ball is moving uniformly c) its force causes no change in distance d) no force acts on the ball

c) its force causes no change is distance

Neglecting air resistance, a skier racing straight down a slope has her greatest speed at... a) difficult to predict without knowing the steepness of the slope b) the top c) the bottom d) difficult to predict without knowing the coefficient of friction e) halfway down

c) the bottom

To lift a 100 kg bad 2 meters, compared to lifting a 50 kg back 4 meters, within the same amount of time requires more power or less power? a) less power b) more information is needed c) the same power d) more power

c) the same power

A rock raised two times as high has a potential energy that is... a) half as much b) impossible to determine unless the time is given c) twice as much d) four times as much

c) twice as much

If you push an object twice as far while applying the same force, you do... a) the same amount of work on both b) half as much work c) twice as much work d) four times as much work

c) twice as much work

An ice skater carries a log across a frozen pond at a constant speed. The amount of work done to the log is... a) more information is needed about the distance traveled b) more information is needed about the weight, distance, and speed c) zero d) more information is needed about the weight of the log e) more information is needed about the speed and the distance

c) zero

It takes 40 J to push a large box 4 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? a) 4 N b) 40 N c) 160 N d) 10 N

d) 10 N

In deep space, two identical 500 kg asteroids glide toward each other, one at 1 m/s and the other at 2 m/s. Just before colliding, their total kinetic energy is... a) 1250 J b) 2500 J c) 7500 J d) 12,500 J e) 10,000 J

d) 12,500 J

A truck traveling four times as fast as a slower-moving identical truck has... a) 12 times the KE b) 8 times the KE c) 4 times the KE d) 16 times the KE

d) 16 times the KE

Within 50 seconds a woman does 100 joules of work. Her power output is... a) 50 W b) 5,000 W c) 4 W d) 2 W e) 1/2 W

d) 2 W

A 100 kg motorcycle rolls slowly off a cliff's edge, falling for 3 seconds to a garbage dump below. Just before hitting the ground its momentum is... a) 400 kg m/s b) 2000 kg m/s c) 1000 kg m/s d) 3000 kg m/s e) 900 kg m/s

d) 3000 kg m/s

While traveling down a highway, a car's engine works against a resistance force averaging 1000 Newtons. The energy to fo this comes from the gasoline, which holds 40 million joules in each liter. So, for every liter of gasoline, how many kilometers can the car travel? Assume 20 percent efficiency. a) 14 kilometers b) 12 kilometers c) 40 kilometers d) 8 kilometers e) 10 kilometers

d) 8 kilometers

When a 2 kg ball is positioned 4 meters above a floor, its potential energy relative to the floor is about... a) 6 J b) 32 J c) 8 J d) 80 J e) 800 J

d) 80 J

A bunch of rocks are thrown upward, each with a different initial velocity. What quantity is the same for each rock? a) maximum height b) time of travel c) initial momentum d) acceleration e) none of these choices are correct

d) acceleration

In deep space, a sticky glob of taffy collides head-on and sticks to an identical glob of taffy at relative rest. After the collision, the Toal momentum remains the same, but the kinetic energy... a) also remains the same b) more information is needed c) increases d) decreases

d) decreases

Five identical steel balls each hanging from a string are lined up at the same height and in a row and in contact with each other. Two balls on one end are together lifted and swung at the remaining three. Two balls on the opposite side pop out. If instead one ball popped out to twice the height, this would violate the conservation of... a) both of these b) none of these c) momentum d) energy

d) energy

When an arrow is shot at twice the speed into a bale of hay, it will penetrate... a) two times deeper b) more than four times as deep c) the same distance d) four times deeper

d) four times deeper

A ball of 1 kilogram and 2 meters above the ground is dropped. It hits the ground and bounces back up to a height of 1.5 meters. About how many joules of energy is lost? a) 2.0 J b) 1.5 J c) 0.5 J d) more than 2.0 J e) 1.0 J

d) more than 2.0 J

A plastic ball and a lead ball of identical size roll down an inclined plane. Half way down they have identical... a) kinetic energies b) inertias c) momentum d) none of these e) potential energies

d) none of these

Once in motion, an object can have a zero amount of... a) kinetic energy b) momentum c) mass d) none of these e) inertia

d) none of these

Two identical jobs. One performed slowly. The other performed quickly. Both will require equal work, but different amounts of... a) effort b) energy c) none of these d) power

d) power

A barrel rolling down a hill his its greatest kinetic energy at... a) three-quarters of the way down b) halfway down c) the top d) the bottom

d) the bottom

To lift a 100 kg bad 2 meters, compared to lifting a 50 kg back 4 meters, requires more work or less work? a) more work b) less work c) more information is needed d) the same amount of work

d) the same amount of work

A barrel rolling down a hill its greatest potential energy at... a) halfway down b) the bottom c) a quarter of the way down d) the top

d) the top

Pushing an object a certain distance, while exerting two times the force, you do... a) four times as much b) half as much work c) the same amount of work d) twice as much work

d) twice as much work

When a 2 kg ball has 40 joules of potential energy relative to the floor, its height above the floor is about... a) 1 m b) 3 m c) 4 m d) 20 m e) 2 m

e) 2 m

It took 1000 joules to lift a crate 10 meters in 20 seconds. The amount of power required to do this was... a) 100 W b) 1000 W c) 20,000 W d) 20 W e) 50 W

e) 50 W

With a system of bullies, a 100 N crate can be lifted 10 meters with 2000 joules of work input, which gives an efficiency of about... a) not enough information b) 80% c) 10% d) 20% e) 50%

e) 50%

A car brakes to a complete stop. This transforms its kinetic energy into... a) the energy of motion b) the energy of rest c) stopping energy d) potential energy e) heat

e) heat