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Homework Help: Amount of force a motor can make in 35s

  1. Feb 16, 2015 #1
    1. The problem statement, all variables and given/known data
    An electric motor develops 65kW of power as it lifts a loaded elevator 17.5 m in 35s. How much force does the motor exert?
    Acceleration: .5
    2. Relevant equations
    F equals mass times acceleration

    3. The attempt at a solution
    Ok so I tried to find mass but when the equation was m equals N divided m/s(squared) but there isn't a weight there. Also I tried the force equation but I can't do that without mass...
  2. jcsd
  3. Feb 16, 2015 #2


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    Power is measured in units of watts, which is a derived unit in the SI system. You are given a distance traveled by the elevator and a time in which to do this, which suggests a certain velocity for the elevator. Is there a formula for power which you can derive that uses force and velocity. Hint: look at the units of each quantity.
  4. Feb 17, 2015 #3


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    Don't be put off by such matters. Just invent an unknown m for the mass and see if you can get enough equations to eliminate it later.
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