# Physics Chapter 7 Hw Part 1

## Unlock all answers in this set

question
W =
Force x Distance
question
The work done in pushing a TV set a distance of 2 m with an average force of 20 N is
40 J
question
The work you do when pushing a shopping cart twice as far while applying the same force is
twice as much
question
The work you do when pushing a shopping cart twice as far while applying twice the force is
four times as much
question
The work you do when pushing a shopping cart a given distance while applying twice as much force is
twice as much
question
No work is done by gravity on a bowling ball that rolls along a bowling alley because
the force on the ball is at right angle's to the balls motion
question
A 1000-kg car and a 2000-kg car are hoisted to the same height. Raising the more massive car requires
twice as much work
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The unit kilowatt-hour is a unit of
energy
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One kilowatt-hour represents
3.6 million joules
question
Which task requires more work? lifting the 25-kg sack 4 meters lifting the 50-kg sack 2 meters
both the same
question
The amount of work done on a heavy box carried by Nellie across a room at a constant speed
is none
question
If you do work on a skateboard loaded with friends in one-third the usual time, you expend
three times the usual power
question
The power expended doing 100 J of work in 50 s is
2 W
question
The power required to exert 4-N force over 3 meters in 2 seconds is
6 W
question
Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time. The power expended in raising the 50-kg sack is
the same
question
A toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed using 1000 J of work, is
50 W
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An object has gravitational potential energy due to its
location
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Relative to an initial height, an object raised twice as high has a gravitational potential energy
twice as much
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A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, its gain in potential energy is
twice as much
question
When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic energy
of 40 J
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A clerk can lift cylindrical packages 1 meter vertically, or can roll them up a 2-meter-long ramp to the same elevation. With the ramp, the applied force required is about
half as much
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A 2-kg ball is held 4 m above the ground. Relative to the ground its potential energy is
80 J
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A 2-kg box of taffy candy has 40 J of potential energy relative to the ground. Its height above the ground is
2 m
question
The ram of a pile driver drops onto the top of an iron beam, driving it partway into the ground. The distance that the beam sinks into the ground depends on the
all of the above; initial energy of the ram, kinetic energy of the ram when it first hits the beam, initial height of the ram
question
An object that has kinetic energy must be
moving
question
Two identical golf carts move at different speeds. The faster cart has twice the speed and therefore has
four times the kinetic energy
question
A feather and a coin dropped in a vacuum fall with equal
accelerations
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A melon is tossed straight upward with 100 J of kinetic energy. If air resistance is negligible the melon will return to its initial level with a kinetic energy of
100 J
question
A melon is projected into the air with 100 J of kinetic energy in the presence of air resistance. When it returns to its initial level its kinetic energy is
less than 100 J
question
Danny Diver weighs 500 N and steps off a diving board 10 m above the water. Danny hits the water with kinetic energy of
5000 J
question
Which has greater kinetic energy?
a car of half the mass traveling at 60 km/hr
question
Neglecting air resistance, Sammy Smarts on a high ladder releases a ball that strikes the ground with 100 J of kinetic energy. If he were to instead throw the ball straight upward, it will soon reach the ground with a kinetic energy of