Two objects have the same mass. One is travelling twice as fast as the other. The work that must be done to stop the faster object compared to the work required to stop the slower object is:
A) four times greater
B) half as great
C) two times greater
D) the same
E) one quarter as great
When a rock is thrown straight up in the air, after it leaves the hand, the rock begins to slow down. This occurs because:
A) the potential energy of the rock decreases as the rock rises.
B) the forces acting on the rock are balanced.
C) the rock is gaining potential energy as it rises, and thus it must lose kinetic energy.
D) the force of gravity acting on the rock increases as the rock rises.