Question

A stone is dropped from a height of 40m calculate spped after 2 s also find speed strike the ground

Answer 1

u=0, s=40, a=10 m/s^(2)

(i) t=2 s

v= u+at

=0+10×2

=20m/s

(ii)v^(2)=u^(2)+2as

=>v^(2)=0+2×10×40

=>v^(2)=800

=>v=root over 800=20×root over 2

Answer 2

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

=0+2×9.8×40

v

=784

v=28m/s

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