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Homework Help: What is the recoil speed of the rifle?

  1. Dec 15, 2009 #1
    1. The problem statement, all variables and given/known data
    Kim holds a 2.0 kg air rifle loosely and fires a bullet of a mass 1.0 g. The muzzle velocity of the bullet is 150 m/s. What is the recoil speed of the rifle?


    2. Relevant equations
    p=mv


    3. The attempt at a solution
    p=(150)(.01) 15=2v
    p=15 7.5=v
     
  2. jcsd
  3. Dec 15, 2009 #2

    rock.freak667

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    Homework Helper

    Re: Momentum

    Looks correct. Just note that it is -7.5m/s
     
  4. Dec 16, 2009 #3

    Borek

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    Staff: Mentor

    Re: Momentum

    No, it is not OK. 1.0g is not 0.01kg.

    Even assuming it is, 150*0.01 is not 15.
     
  5. Dec 16, 2009 #4
    Re: Momentum

    I apologize wasn't what i had on my paper in a bit of rush to see if i was understanding the equation. You are absolutely right 1 g is .001kg and it multiplied by 150 is 1.5, but besides careless errors i just want 2 know am i on the right track
     
  6. Dec 16, 2009 #5

    Borek

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    Staff: Mentor

    Re: Momentum

    General approach seems to be OK :smile:
     
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