Question

A stone is dropped from a height of 40 m.
(a) How much time will it take to reach the ground?
(b) With what velocity will it strike the ground?
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Answer 1

Given that,

Height = 40 m

Time t =2 sec

We know that,

v=u+gt

v=0+9.8×2

v=19.6m/s

The speed of stone is 19.6 m/s

Now, the speed with which the stone strikes the ground

v

2

=u

2

+2gs

v

2

=0+2×9.8×40

v

2

=784

v=28m/s

Hence, the speed with which the stone strikes the ground is 28 m/s