posted by t on .
How long would it take a 20.0 hp motor to lift a 1,000.0 kg crate from the bottom of a freighter's hold to the deck (40.0 m)?
The work required is
M*g*H = 1000*9.81*40 = 3.92*10^5 Joules
A 20 HP motor can provide 20*746 = 14,920 watts (J/sec) of power.
I get 26.3 seconds