A 7 kilogram bowling ball is dropped from a fourth story window. If each story is 3 meters high, use energy conservation (not the equations of motion) to find the ball's velocity when it strikes the ground. Ignore air resistance.

1/2 m v^2= mgh
v= sqrt (2g*(3+.5))

V=sqrt(2)(9.8)(3)
v=sqrt58.8
v=7.67 m/s

did I do this right? thanks

The approach is correct...and the answer is correct for a one storey building.

Replace (3+0.5) by (3*3+1)
3 storeys+1m above floor.