1. You drop a rock off a bridge. When the rock has fallen 4m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities?
(a) Both increase at the same rate.
(b) The velocity of the first rock increases faster than the velocity of the second.
(c) The velocity of the second rock increases faster than the velocity of the first.
(d) Both velocities stay constant.
2. You drive 4 km at 30 km/h and then another 4 km at 50 km/h. What is your average speed for the whole 8-km trip?
(a) More than 40 km/h.
(b) Equal to 40 km/h.
(c) Less than 40 km/h.
(d) Not enough information.
3. A ball is dropped from the top of a tall building. At the same instant, a second ball is thrown upward from the ground level. When the two balls pass one another, one on the way up, the other on the way down, compare the magnitudes of their acceleration:
(a) The acceleration of the dropped ball is greater.
(b) The acceleration of the ball thrown upward is greater.
(c) The acceleration of both balls is the same.
(d) The acceleration changes during the motion, so you cannot predict the exact value when the two balls pass each other.
(e) The accelerations are in opposite directions.