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Power and Force

  1. Jun 3, 2006 #1
    Hi guys,

    I've got one question couldn't figure out over the night. Here goes:

    A trolley is accelerated by a constant force from a motor. If friction forces can be neglected, what would the graph of the power of the motor against time be like?

    My answer is a straight horizontal line for some value of P. The answer I was given was a straight line graph from the origin with a postiive gradient. Why is this so? My reasoning is that the motor supplies a constant force which would necessary mean the rate of doing work is constant?

  2. jcsd
  3. Jun 3, 2006 #2

    Doc Al

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    Staff: Mentor

    While the force is constant, the speed is increasing. The work required to move the trolley a given distance will remain the same, but as the trolley speeds up that same work must be done in a shorter amount of time.
  4. Jun 3, 2006 #3
    Thanks Doc Al it didn't occur to me.
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