Energy Conservation

Pendulum swinging with no air friction

Imagine a pendulum with no air friction. In this case, the pendulum will rise to its original height. How does the potential energy at one end of the swing compare to the potential energy at the other end?

They are equal

They are not equal

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Is potential energy conserved?

In an example of a pendulum swinging with no air friction. The pendulum will rise to its original height and potential energy at one end point is equal to the other end point. Can we say that potential energy is conserved in this case?

Yes

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Why a swinging pendulum does not rise to exactly the same height it initially started from on the other side?

Because it does work on the surrounding air

Because of its weight

Because of gravity

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Which pendulum will rise to almost the same height it started from?

A pendulum that moves fast

A pendulum that moves slower

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Consider the pendulum that hits a shoe at the bottom of its motion

The kinetic energy of the pendulum just before it hits the shoe is the potential energy it lost in falling from the left end of its swing.

In fact, if we ignore air friction and if the shoe were not there, the potential energy attained on the right end of the swing would be equal to the kinetic energy at the bottom. Now consider the effect of friction, and compare the potential energy at the right end of the swing to the potential energy originally at the left.

If friction is present, how will the potential energy at the right compare to that on the left?

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equal to

greater than

less than

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The conservation of energy applies during the _______ fall of an object

initial

entire

end

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During the fall of an object

At any time, the in potential energy is equal to the in kinetic energy

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decrease

increase

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The total of the kinetic and potential energy is __________

increasing

decreasing

constant

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The law of conservation of energy can be stated as follows

The total energy at the end of any event is equal to the total energy the event

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A swinging pendulum starting from the left loses some energy in a form of a _______

Missing

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At the point where a pendulum has lost 9 joules of potential energy, how much kinetic energy has it gained?

Just right the number

Missing

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How much potential energy is needed to develop 15 joules of kinetic energy?

Write numbers only

Missing

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Suppose the pendulum has 20 joules of potential energy at the top of its swing

When the pendulum is partway down, its PE is 12 joules. How much kinetic energy does it have at this point?

Write the answer in numbers

Missing

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A pool ball hits a second one at rest and the second one assumes the velocity of the first

there is no kinetic energy lost and such a collision is said to be

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elastic

inelastic

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When two cars collide, is the collision normally elastic or inelastic?

elastic

inelastic

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