Question

A baseball pitcher throws the ball with an initial speed of 40 m/s. At the instant of release
the velocity is directed horizontally and the ball is 2.1 m above the ground and 20 m
(horizontally) from home plate.
a) How long does it take to pass over the plate?
b) As it crosses the plate, what is its height above the ground?

Answer 1

Answer:

When the ball reaches the highest point, its velocity will be zero. So final velocity is v=0m/s

Here, the time to reach highest point is equal to time to hit ground from highest point.

Consider upward motion, the acceleration of the ball is a=−g=−9.8m/s

2

(minus for motion opposite to gravity)

If t be the required time.

Using v=u+at,

0=25+(−9.8)t

⟹ t=2.5s

Thus the ball hits the ground after 2.5 seconds after reaching its highest point.

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