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Work done climbing a flight of stairs.

  1. Oct 18, 2009 #1
    A 58 kg firefighter climbs a flight of stairs 5.3 m high. How much work is required?

    I know work is just force times distance, but I'm not given a force? And I can't really find a force because force is mass times acceleration and I'm not given an acceleration...help!
     
  2. jcsd
  3. Oct 18, 2009 #2

    mgb_phys

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    Do you know about gravitational potential energy?

    Actually you are given a force, if he has a mass of 58kg (you must have some skinny firemen!) and he is on Earth, how much does he weigh?
     
  4. Oct 18, 2009 #3
    9.8 times 58...so 568.4 N right? Then 568.4 times 5.3m and you get 3012.52, yes? Would the unit be joules?
     
  5. Oct 18, 2009 #4

    mgb_phys

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    Yes - but think about how many significant figures you should have

    The equation for potential energy = m g h
    As you said this is the same as force (mg) * distance (h)
    And yes J = N m = kg m^2/s^2
     
  6. Oct 18, 2009 #5
    Would it just be 3.0 times 10^3 in correct sig figs?
     
    Last edited: Oct 18, 2009
  7. Oct 18, 2009 #6
    ?????
     
  8. Oct 18, 2009 #7

    mgb_phys

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    Yes, you have 2 sig figures for the mass and height so it's two sig figures for the answer.
    So formally 3.0 x 10^3 J or 3000J would probably be ok.
     
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