Question

A 30-kg stone is dropped from a height of 100m. find its KE and PE when it is 50 m from the ground

Answer 1

MEf=MEi

KE=1/2mv^2

PE=mgh

mgh+1/2mv^2=mgh+1/2mv^2

Vi=0

So,

mgh=mgh+1/2mv^2

mgh=mgh+KE

(30*9.8*100)-(30*9.8*50)=KE

30(980-490)=KE

KE=30*490=14.7kj

Answer 2

PE@50m=KE@50m