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Homework Help: How much horsepower are you applying?

  1. Nov 10, 2008 #1
    1. The problem statement, all variables and given/known data

    You are towing a car on a level road at a constant speed of 20 m/sec. A scale attatched to the rope measures a force of 200 N. How much horsepower are you applying to the towed car to keep it moving? (Note 1 HP = 746 W).

    Please help I have a physics test tomorrow. Thanks and please be detailed!


    2. Relevant equations

    F = MA

    3. The attempt at a solution

    A = 20 m/s
    F= 200 N

    F=MA
    200 N = M(20m/s)
     
  2. jcsd
  3. Nov 10, 2008 #2

    mgb_phys

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    Try energy is force * distance
    and power = energy / time
     
  4. Nov 10, 2008 #3
    That didn't help miuch. Can anyone else help me?
     
  5. Nov 10, 2008 #4

    mgb_phys

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    Work (ie energy) is force * distance
    How much force are you applying?
    How much distance are you travelling in 1second?
    Power is work/time, so how much work did you do in 1second.
     
  6. Nov 10, 2008 #5
    Well it should, because the answer is right there.

    Power = force * distance / time

    So, you can calculate the power if you know how much force it requires to move the object over a certain distance within a certain period of time

    marlon
     
  7. Nov 10, 2008 #6
    Wow! I cannot believe I finally got this questioN! THanks. The problem was I did not know that formula and I can not find it in my book anywhere ...
     
  8. Nov 10, 2008 #7
    What formula ?

    I find it quite hard to believe your book wouldn't mention one of the formula's cited above

    marlon
     
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