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Energy problem

  1. Apr 17, 2005 #1
    A battery is being charged by a voltage v=11+0.5t V and a constant current of 2 A. The price of a kWh is 10 cent. How much is 5 hours battery-charging?

    My work:
    p = 22 + t
    [tex]w= \int_{0}^{5} x dt = 25/5 + 22*5 = 122.5 W[/tex]
    122.5 W in 5 h = 5 * 122.5 Wh = 0.6125 kWh
     
  2. jcsd
  3. Apr 17, 2005 #2
    [tex]w= \int_{0}^{5} p(t) dt[/tex]

    where p = VA = 22 + 1t correct?

    Just integrate that from zero to five to get the power then do the last step... i think its correct.

    you should end up getting 122.5 JOULES like you did... your answer is correct.

    Just make sure your units are right.
     
    Last edited: Apr 17, 2005
  4. Apr 19, 2005 #3
    I solved it. I did indeed just need to crack the units.
     
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