John throws a rock down with speed 20 m/s from the top of a 30-m ...

[karlynnae]

John throws a rock down with speed 20 m/s from the top of a 30-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the rock's speed just as it hits the ground?
 a. 12 m/s
  c. 31 m/s
  b. 28 m/s
  d. 78 m/s

Question 2

Gwen releases a rock at rest from the top of a 50-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the speed of the rock as it hits the ground?
 a. 28 m/s
  c. 56 m/s
  b. 31 m/s
  d. 784 m/s

[otokexnaru]

Answer to Question 1

C

Answer to Question 2

B