A rock is dropped from rest off of a high cliff on another planet, planet X. There is no atmosphere, and thus no air resistance, on planet X. At the end of 1 second, the rock is moving at a speed of 6 m/s. What is the rock's average speed during the entire first second [from t=0 until t=1 sec]?
A) 10 m/s
B) 5 m/s
C) 6 m/s
D) 0
E) 3 m/s

Question

Quizplus · Accepted Answer

The average speed is the total distance traveled divided by the total time. Since the rock starts from rest and accelerates uniformly to 6 m/s in 1 second, the average speed is (0 + 6)/2 = 3 m/s.

A Rock Is Dropped from Rest Off of a High