Jim is playing with a 1-meter-long pendulum that is hooked

2 meters above the ground. He lifts the pendulum's bob to a height of 2 meters above the ground and then releases it. Potential energy is assigned zero value at the ground level. Which statement is true about this problem?

AAt the lowest position of the bob,the KE is equal to zero.
BAt the highest position of bob, PE is equal to zero.
CAt the highest position of the bob, the KE is equal to zero.
DAt all the positions except the highest positions the PE is zero.

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Verified Answer :

kikyry kikyry · Answer 1 · 2016-12-13T15:15:11-05:00

the answer would be C.

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aristocles aristocles · Answer 2 · 2019-10-05T22:54:14-04:00

Answer:

C. At the highest position of the bob, the KE is equal to zero.

Explanation:

When pendulum bob is at highest position then the bob is released from rest position

So at that instant of time the pendulum bob is at rest position so we can say that

initial total energy = kinetic energy + potential energy

As we have taken the ground position as reference so at the ground potential energy is zero

Since pendulum will never touch the ground position so here potential energy of pendulum never equal to zero

Now when pendulum is released its potential energy will convert into kinetic energy

So here correct answer will be

C. At the highest position of the bob, the KE is equal to zero.