Two cyclists who weigh the same and have identical bicycles ride up the same mountain,both starting at the same time.Joe rides straight up the mountain,and Bob rides up the longer road that has a lower grade.Joe gets to the top before Bob.Ignoring friction and wind resistance,which one of the following statements is true?
A)The amount of internal energy converted to gravitational potential energy of the system Joe- Earth is equal to the amount of of internal energy converted to gravitational potential energy of the system Bob-Earth, but the average power of the process for Joe is greater than that for Bob.
B)The amount of internal energy converted to gravitational potential energy of the system Joe- Earth is greater than the amount of internal energy converted to gravitational potential energy of the system Bob-Earth, and the average power of the process for Joe is greater than that for Bob.
C)Bob and Joe converted the same amount of internal energy to gravitational potential energy, and the average power of the process for each cyclist was also the same.
D)The average power of the process for Bob and Joe was the same, but Joe converted more of the internal energy into the gravitational potential energy in getting there.

Question

Quizplus · Accepted Answer

The amount of internal energy converted to gravitational potential energy for both Joe and Bob is the same because they both reach the same height, which means they have the same increase in gravitational potential energy. However, since Joe gets to the top before Bob, Joe does this in a shorter amount of time, indicating that Joe's average power (energy per unit time) is greater than Bob's.

Two Cyclists Who Weigh the Same and Have Identical Bicycles