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/, = 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 *.