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V (t ) = 5sin (t ) [V]

  1. May 7, 2009 #1
    1. A circuit element is shown below, with the voltage v(t) and the current i(t) defined. The
    voltage and current are given as
    v (t ) = 5sin (t ) [V]
    i (t ) = −10cos (t ) [A] .
    Calculate the power that the element is delivering.

    b) For the same circuit in the previous problem, calculate the amount of energy that the circuit
    element absorbs between t = 0 and t = 1 .


    I don't get the b0 part. The solution for the first part is 50 sin(t) cos(t) [W]. How do I get the amount of energy for that time frame?
     
  2. jcsd
  3. May 7, 2009 #2

    berkeman

    User Avatar

    Staff: Mentor

    Re: circuits



    What kind of a circuit element is it? Why are they asking about delivering power in one part, and absorbing power in the other part?

    To get energy over a time period, you just integrate the power multiplied by dt over the time interval.
     
  4. May 7, 2009 #3
    Re: circuits

    I forgot how to take the integral of cos/sin :confused:

    u= sin(t) du=cos(t) dt

    Maybe you can explain the next step to me:) I think that once I got the result of it I am done.
     
  5. May 7, 2009 #4

    berkeman

    User Avatar

    Staff: Mentor

    Re: circuits

    The wikipedia.org article on integration by parts is pretty reasonable:

    http://en.wikipedia.org/wiki/Integration_by_parts

    .
     
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