Power question

[steelcap]

Hey everyone, just wondering if anyone can help me out with a homework question I'm having trouble with. I've been stuck on it for about 45 minutes now, any help will be appreciated. Thanks.

"A conveyor belt is driven by a motor rated at 60kW. Only 90% of the rated power is available for useful work. The coal is to be raised and deposited into a hopper 19.5m above. How many kilograms of coal can be delivered by this motor per minute?"

- Matt

[ek]

If you use t = 60s, then find the mass through work/potential energy considerations.

P = \frac {W}{t}

W = mgh

P = \frac {mgh}{t}

m = \frac {Pt}{gh}

[check]

Dont forget to forget to multiply the power by the motor's efficiency!