Question

A coin is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10$m/s^2$, with what velocity and after what time will it strike the ground?

• A. 20m/s, 2s
• B. 10m/s, 1 s
• C. 30m/s, 2s
• D. 20m/s, 5s

Answer 1

The correct option is A

20m/s, 2s

Here,

u = 0 , s = 20m , a =10$m/s^2$

$v^2$ = $u^2$ + 2as

$v^2$= 0 + (2 x 10 x 20)

$v^2$ = 400

v = 20 m/s

Hence the velocity with which it strikes teh ground is 20 m/s.

Also,

v = u + at

20 = 0 + 10t

t = 2s