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Homework Help: Need Help with This Problem (Urgent)

  1. Sep 26, 2005 #1
    What is the efficiency of a 265W motor that draws 4.30A from 120V line?
    How much energy in Joules does this motor use in 1.50 hour?

    thanks in advance..
  2. jcsd
  3. Sep 27, 2005 #2
    What have you tried? Do you know what power is?
  4. Sep 27, 2005 #3
    power has two equations :
    1) P(t)= W/t = -PE/t = q.V/t = I.V
    2) P= I (I.R)
  5. Sep 27, 2005 #4
    Power can also be expressed as P=V^2/R

    Now what is efficiency defined as?

    Finally, what information are you given and what can you do with it?
  6. Sep 27, 2005 #5


    User Avatar

    If W/t=IV

    You just plug it in, then find the efficiency.
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