Question

A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10ms^-2 , with what velocity will it strike the ground? After what time will it strike the ground?

Answer 1

Here, u = 0 m/s, s = 20 m, 

a = 10 ms^-2 , 

v = ?, 

t = ? 

Using v ² – u ² = 2as 

We have, v ² – 0 ² = 2 × 10 × 20 = 400 ⇒ v = 20 ms^-1 . 

and t = (v – u) ÷ a = 20 ÷ 10 = 2 s.