43. A cart is released from rest at the top of a hill and rolls to the bottom. In the absence of friction and air drag, the cart will have the highest kinetic energy at the
Answer: D
The cart will have the highest kinetic energy at the bottom of the hill.
As the cart rolls down the hill, it converts potential energy into kinetic energy. At the bottom of the hill, all the potential energy has been converted into kinetic energy, resulting in the highest kinetic energy at this point.
A) top of the hill
At the top of the hill, the cart has maximum potential energy and zero kinetic energy since it is at rest. Therefore, it cannot have the highest kinetic energy at this position.
B) just below the top of the hill
Just below the top of the hill, the cart begins to convert some of its potential energy into kinetic energy, but it has not reached the maximum kinetic energy it will achieve at the bottom of the hill. Thus, it does not have the highest kinetic energy at this point.
C) midpoint of the hill
At the midpoint of the hill, the cart has converted some potential energy into kinetic energy, but it is still not at its maximum kinetic energy. The kinetic energy will continue to increase as the cart descends further down the hill.
D) bottom of the hill
At the bottom of the hill, the cart has converted all of its initial potential energy into kinetic energy, resulting in the highest kinetic energy it will achieve during its descent. This makes this option the correct choice.
Conclusion
The correct answer is that the cart has the highest kinetic energy at the bottom of the hill because it has fully converted its potential energy into kinetic energy by that point. All other options reflect positions where the cart has not yet achieved maximum kinetic energy, as potential energy is still present and has not been fully converted.