Question

A cricket ball is drop from the height of 20m. calculate the speed of ball when he hits the ground and calculate the time it takes to fall through his height.

Answer 1

Height from which the ball is dropped (H) = 20 m

Initial speed (u) = 0 m/s

Acceleration due to gravity (a) = 9.8 m/s^2

Let the final speed at the ground be v.

$v^2 = u^2 + 2aH$

$v^2 = 0 + 2 \times 9.8 \times 20$

$v = \sqrt{392}$

v = 19.79 m/s

Hence, the velocity at the bottom is 19.79 m/s

Now, let the time taken to reach the ground be t.

$v = u + at$

$t = \frac{v-u}{a}$

$t = \frac{19.79}{9.8}$

t = 2.02 seconds

Hence, the time taken to reach the ground is 2.02 seconds