Question

A ball of mass 0.5kg slows down from a speed of 5ms^-1 to that of 3ms^-1. Calculate the change in kinetic energy of the ball

Answer 1

mass=0.5kg
initial velocity=5m/s2
so
initial kinetic energy=1/2mv2
=1/2*0.5*5*5=6.25
final velocity=3m/s2
so final K.E.=1/2*0.5*3*3
=2.25
so change inK.E.=6.25-2.25
=4 j

Answer 2

k. e. of first body=1/2 mvsqure
1/2 0.5*25=1/2*12.5 this is 1st eq.
k. e of 2nd =1/2*0.5*9=1/2*4.5and solveit