a stone of mass 3kg is falling from rest from the top ofa hill.what will be its K.E. after 3s.if the hill is 100m high,what will be its K.E.just before hitting the ground.

Dear student

Given mass= 3 kg

u =0

t=3 s

using the equation, v=u+at

v= 10 x 3 = 30m/s

KE after 3 sec = (1/2)x 3 x (30)^2 J

 

Given h = 100m

Velocity just before striking the ground,

v^2-u^2 = 2ah

v^2 = 2 x 100 x 10=2000

v = m/s

So KE= (1/2)x 3 x (20√5)^2 J

 

Regards

Team

Topperlearning