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Force on an object problem

  1. Jan 20, 2009 #1
    1. The problem statement, all variables and given/known data
    A gun weighs 10lbs and the barrel length is 10.2 inches. It fires a .45 caliber bulect weighing .0328lbs at a speed of 918ft/s. How much force is exerted on the bullet when fired?


    2. Relevant equations
    F=ma


    3. The attempt at a solution
    Here is what I did. Keep in mind that it is wrong, but when I did it I believed it to the correct method.
    Vi=0
    vf=918
    s=.85 ft
    a=?
    918^2=1.7a
    a=495720ft/s(squared)

    F=ma
    F=.3105kg(495720)
    F=153921.06 N

    TRIED IT AGAIN:
    MbAb=MgAg
    (.001018634)(495720)=.3105a
    a=1626.27
    F=ma
    F=(.3105)(1626.27)
    F=504.95(aprox.)
    Is this correct?

    If not, what should I do instead?
     
    Last edited: Jan 20, 2009
  2. jcsd
  3. Jan 20, 2009 #2
    F=ma
    F=.3105kg(495720)

    I think you switched to the metric system for the mass.
     
  4. Jan 20, 2009 #3
    so was my 1st method right or was the second method right?
     
  5. Jan 20, 2009 #4
    I'm not sure what your second method is. But the first method looks fine up to the F=ma.
     
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