Question

a stone is dropped from the top of a 40 metre high tower.calculate its speed after 2 second. also find the speed with which the stone hits the ground

Answer 1

Distance =40m
we know that,
1m=100cm
40m=4000cm
Time taken=2 sec
speed=distance ÷time
4000cm÷2 sec
= 2000cm/sec
I don't kno how to calculate its speed after 2 sec

Answer 2

u = 0 a=9.8 t= 2
v=u+at
=0+9.8×2
=19.6m/s
So, speed after 2 second is 19.6m/s
v^2=u^2+2as
=0^2+2×9.8×40=19.6×40=196×4
=> v=√196×4=28m/s.
So, the body will hit the ground with a speed 28m/s.