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Quick power/hp question

  1. Jan 14, 2008 #1
    1. The problem statement, all variables and given/known data

    how do u get from power to horsepower?
    mass=60 kg
    weight=588.6 N
    height=7 m
    time=6.45 s
    power= 638.79 W

    2. Relevant equations

    ----

    3. The attempt at a solution

    multiply by 746 W to get: 476537.34 hp
    or divide by 746 W to get: .856286 hp

    i think its divide rather than multiply b/c then the watts cancel and ure left with hp, but im not sure. thats my only question. multiply or divide?
     
  2. jcsd
  3. Jan 14, 2008 #2

    mgb_phys

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    Science Advisor
    Homework Helper

    1 horsepower = 745.7 watts
    or 1 W = 1/745.7 Hp, so you replace the 'W' with (1/745.7)Hp.

    Or just think would 638W be more or less than 1 hp and roughly how many would it be?
    It's always worth estimating the answer before putting the numbers in a calculator.
     
    Last edited: Jan 14, 2008
  4. Jan 14, 2008 #3
    less. so IT IS divide. thanks. i knew 400,000 hp was unreasonable for a person. this was a lab btw.
     
    Last edited: Jan 14, 2008
  5. Jan 14, 2008 #4

    berkeman

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    Staff: Mentor

    You have the correct instinct that you should be able to carry your units along in your calculation to help you keep the numbers in the right places. Here's a thread that should help your insight -- check out my post #10 and the subsequent comments:

    https://www.physicsforums.com/showthread.php?t=130989

    Very important trick to use and master in your math and physics and engineering studies!
     
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