How much work is done in an hour?

[kriegera]

Homework Statement

A man pumps water at a rate of 20 liters per minute to a height of 10 meters. How much work does he do in an hour? Friction is to be neglected. A liter of water is taken to weigh 1 kilogram.

Homework Equations

The Attempt at a Solution

If 1 liter=1 Kilogram then 20 liters = 20 kg
Work is a kind of energy conversion. The work done per unit of time is
P= ΔE/ ΔT = (20)(9.8)(10)/(60minutes) = 32.67J/minute

Is this correct? I'm unsure about the conversions?

 

[willem2]

Your answer for the power is correct, but you should divide by 60 seconds, not 60 minutes, and the answer would then be in J/s, or W You need to multiply that with the number of seconds in an hour to get the answer to the question.

 

[kriegera]

So the correct answer would be:
P = ΔE/ ΔT = (20)(9.8)(10)/(60seconds) = 32.67J/seconds