A heavy stone is dropped from rest and the effects of air resistance can be neglected. As the stone falls, which of the following statements is always true?
a. The gravitational potential energy is conserved.
b. The stone’s kinetic energy of motion is conserved.
c. Both the total mechanical energy and the momentum of the stone are conserved.
d. The momentum of the stone is conserved.
e. The total mechanical energy is conserved but the momentum is not conserved.