Time to Lift 50 15.0-kg Boxes at 41.4 W Output

[mphysicsdc]

Homework Statement

If a man has an average useful power output of 41.4 W, what minimum time would it take him to lift fifty 15.0-kg boxes to a height of 1.88 m?

Homework Equations

1/2mv(final)^2 mgy(final) = 1/2mv(initial)^2 mgy(initial)

P=W/Δt

P=Fv

The Attempt at a Solution

Dont even know where to start

 

[ideasrule]

How much energy is needed to lift those boxes?