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

1. Oct 17, 2011

reefcake

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. Oct 17, 2011

SammyS

Staff Emeritus
Welcome to PH.

After the collision, what momentum will Car A have if momentum is really conserved?

3. Oct 17, 2011

reefcake

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