. A ball 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 will it strike the ground? After what time will it strike the ground

Best Answer

Sol. Given,

Initial velocity, u = 0 (As the ball is dropped from rest)

Final velocity, v =?

Acceleration, a = 10 m/s2

Distance, s = 20 m

We know that,

v2 = u2 + 2as

v2 = (0)2 + 2 × 10 × 20

v2 = 0 + 400

v2 = 400

v = 20 m/s

Now we have to calculate the time taken:

We know that:

v = u + at

20 = 0 + 10 × t

10t = 20

t =  20/10

t = 2 s

Therefore, after 2 seconds the ball will strike the ground.

 

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