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How much power physics question

  1. Aug 5, 2014 #1
    For example, if it takes 60 watts of Power for a machine to fly, yet loses (for instance) 2.5 * 10^3 Joules of its energy because of the air resistance, whats the amount of "Power" that was really given in the first place?
     
  2. jcsd
  3. Aug 5, 2014 #2
    I'm not sure I totally understand the problem but a watt is a joule/second, so if the plane needs 60 joules per second to maintain its velocity but loses 2500 joules per second because of air resistance, then the power required would be 2500 watts + 60 watts no?
     
  4. Aug 5, 2014 #3

    Simon Bridge

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    Since the power is energy per second - and you have only given a total energy figure for the amount lost to air resistance, then it is not possible to calculate the "real" power without also knowing the time of flight.

    But I suspect you just need to reword the question to make it clear.
     
  5. Aug 5, 2014 #4
    The time of flight is 30 minutes to reach a height of 2230 meters
     
  6. Aug 5, 2014 #5
     
  7. Aug 5, 2014 #6

    Simon Bridge

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    So if you lost 2500J in 30mins... How many J in 1sec?
     
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