What impulse was given to the ball?

Question

A ball of mass 0.120 kg is dropped from rest from a height of 1.25 m. It rebounds from the floor to reach a height of 0.600 m. What impulse was given to the ball by the floor in kg*m/s?

Answer 1

Just equate the kinetic and potential energies: .5mv^2=mgh
This means that v= sqrt(2gh)=sqrt(2*9.8*.6)=3.42m/s; therefore, the impulse is .12*3.43=.411.