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Working out the speed a parked car travels after a moving car hits it

  1. Oct 17, 2011 #1
    Hi I'm forensics student and I'm having trouble with this problem as i don't know how to solve it I would really like to to know the method.

    1. The problem statement, all variables and given/known data
    Calculate the speed in ms-1 at which a parked 1840kg "car A" will be travelling once "car B" crashes in to it. assuming that "car B" continues to move forward at 8.4ms-1 after the crash.

    info on Car A: Mass(m)= 1840kg, Speed(v)=0 ms-1

    info on Car B: Mass(m)= 1400kg, Speed(v)= 26.82 ms-1 Momentum(p), 37548 kg-ms-1
    ending speed= 8.4ms-1, Ending momentum= 11760 kg-ms-1

    2. Relevant equations
    p=mv (conservation momentum)
    F=ma (newtons 2nd law of motion)
    A= uv/t (working out acceleration)



    Thanks

    reefcake
     
  2. jcsd
  3. Oct 17, 2011 #2

    SammyS

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    Welcome to PH.

    After the collision, what momentum will Car A have if momentum is really conserved?
     
  4. Oct 17, 2011 #3
    Hi again ;)

    yes that is problem as I'm not sure to go about working out as Car B transfers (p)25788kg-ms to car a but Car A is 1840kg, 440 kg heavier. do i divide (p)25788kg-ms (which is the transferred momentum) by 1840kg to get the speed of CarA?

    thanks
     
    Last edited: Oct 17, 2011
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