1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Power question

  1. Nov 21, 2004 #1
    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
  2. jcsd
  3. Nov 21, 2004 #2


    User Avatar

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

    [tex]P = \frac {W}{t}[/tex]

    [tex]W = mgh[/tex]

    [tex]P = \frac {mgh}{t}[/tex]

    [tex]m = \frac {Pt}{gh}[/tex]
  4. Nov 21, 2004 #3
    Dont forget to forget to multiply the power by the motor's efficiency!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook