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Homework Help: Quick Kinetic Energy question - only confirmation of answer needed.

  1. Oct 17, 2009 #1
    Hi guys,

    Calculate the change in kinetic energy of a car of mass 2000kg if it changes its velocity from 30km/h to 60km/h


    So, to find the change in KE, subtract its KE when it was going 30km/h from when it was going 60km/h.

    At 30km/h:

    At 60km/h:

    So change in KE is 209501-69389
    = 209501J

    Is that correct, or am I doing it totally wrong?

    Also - "explain the source of the energy gain" - would that just be an increase in velocity?
  2. jcsd
  3. Oct 17, 2009 #2


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    Homework Helper

    Yes that is correct. The source would be what is producing motion in the car in the first place. So this would be the?
  4. Oct 17, 2009 #3
    The driving force/friction between the tires and the road?
  5. Oct 17, 2009 #4


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    Homework Helper

    Well I'd just say it is the engine.
  6. Oct 17, 2009 #5
    Alright great, thanks for your help! :)
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