Question

A ball is thrown vertically upward from a 75-m-tall building with an initial speed of 20 m/s. The ball misses the building on its way down and hits the ground. What is the final velocity of the ball just before it hits the ground?

a) 20 m/s
b) 0 m/s
c) -20 m/s
d) None of these

Answer 1

The final velocity of the ball just before it hits the ground is -20 m/s.

Step-by-step explanation:

When a ball is thrown vertically upward, its final velocity just before it hits the ground is 20 m/s.

The ball is thrown upward with an initial speed of 20 m/s. As it reaches its maximum height, its speed becomes zero. On its way back down, the ball experiences the same acceleration due to gravity as in free fall, which is approximately 9.8 m/s^2.
The final velocity of the ball just before it hits the ground is equal to the magnitude of its initial velocity, but in the opposite direction. Therefore, the final velocity of the ball just before it hits the ground is -20 m/s.