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Questions in final

  1. May 24, 2008 #1
    1. The problem statement, all variables and given/known data
    I just gave my physics final and i want to confirm if my answers are correct
    the kinetic energy of a particle is increased by factor 4 how much will linear momentum will increase show mathematical steps
    how much is the power output of the engine of a 1000 kg car can go from 36km/h to 108km/h in 10 seconds.
    two bodies of mass 2 kg and 5 kg are placed separated by 40cm in air.Assuming the force acting on them are due to gravitational interaction,calculate their frequencies



    2. Relevant equations



    3. The attempt at a solution
     
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  3. May 24, 2008 #2

    Redbelly98

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    If you post your answers, we can confirm them.
     
  4. May 24, 2008 #3
    I really cant recall what I wrote in those questions..but my answer to the last one was that both bodies are freely falling so gravitational acceleration will be the acceleration of both the bodies
    and in the first one may anwer was that momentum increases 4 times
     
  5. May 24, 2008 #4

    Redbelly98

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    The last one is confusing to me. I don't actually understand the question, but it does ask to calculate frequencies and your answer does not give a frequency.

    For the first one, no, it will not increase 4 times. You need to use the equations for kinetic energy and momentum, and work with those equations.
     
  6. May 24, 2008 #5
    [tex]K = \frac{p^{2}}{2m}[/tex]
     
  7. May 24, 2008 #6
    Well we have to find the acclerations not the frequencies..sorry,a tryping mistake..whta about the second question?
     
  8. May 25, 2008 #7

    Redbelly98

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    If you calculate the force on the two masses, you can get the accelerations.

    What is the basic equation that defines power? Use that.
     
  9. May 26, 2008 #8
    I calculated the force on the tow masses by multiplying thier masses with 9.8m/s-2 and i got the acceleration 9.8 m/s-2...and in the second question i used the power =force *velocity.it would be really helpful ifyou could provide the complete solution to the second question thanks sooooooooo much
     
  10. May 28, 2008 #9

    Redbelly98

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    I haven't solved the 2nd problem, but to solve it I would have used:
    Power = (change in energy) / (time)

    For the last question, I interpreted it to mean you use the force the masses exert on each other.
     
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