In the "before" part of Fig. 9-60, car A (mass 1100 kg) is stopped at a traffic light when it is rear-ended by car B (mass 1500 kg). Both cars then slide with locked wheels until the frictional force from the slick road (with a low μk of 0.21) stops them, at distances dA = 5.3 m and dB = 3.4 m. What are the speeds of (a) car A and (b) car B at the start of the sliding, just after the collision? (c) Assuming that linear momentum is conserved during the collision, find the speed of car B just before the collision.
(see attachment for image)
(A = CarA, B = CarB)
PAi + PBi = PAf + PBf
(mA)vAi + (mB)vBi = (mA)vAf + (mB)vBf
The Attempt at a Solution
I've been sitting here looking blankly at this problem for about an hour now. I really have no idea where to start with this, i've tried a few things, but it always ends up giving me two unknown variables. Looking at another thread that was posted on this question, I realize that all the kinetic energy is transferred to thermal in the end, how does that help?