Free Fall: A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct?
A. On the way up, its acceleration is downward and its velocity is upward, and at the highest point both its velocity and acceleration are zero.
B. On the way down, both its velocity and acceleration are downward, and at the highest point both its velocity and acceleration are zero.
C. Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration.
D. The acceleration is downward at all points in the motion.
E. The acceleration is downward at all points in the motion except that is zero at the highest point.
Answer: D
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