1. The problem statement, all variables and given/known data This lab I have the mass and change in distance measurements for inelastic collisions; and then we did an elastic collision one where we determined the mass and measured the times three of them simultaneously where we measured it as it bumped the car. So I am supposed to prove the law of conservation of momentum, but i have no clue which equation I am supposed to start with. For the measurements on the inelastic collisions I got a mass of 66.3 for change in distance of 3 feet, and 266.3 for 2.12 feet, and 366.3 for 1.88 feet. For the elastic mass of 66.3 or .0663 kg and the times we got as it bumped each car, simultaneously were 1.17 sec, .13 sec, and 1.32 sec. I believe that we are supposed to compare the ratio to determine the ratio of distances is equal to the ratio of masses and therefore show that momentum is conserved. We also are supposed to use KE somehow, but not in the inelastic collision. How would I get V? Or how would I start? I don't have any time measurements for the first one tho. I feel like I am over thinking this. Thanks beforehand if you can help me. 2. Relevant equations I was thinking I need to use mVa+mVa=mVb+mVb and then mVa+mVb=0 So mVa= -mVb but I don't have V So would I use Va*t=Da and Va*t=Db so Va/Vb=Da/Db and then Ma*Da= -Ma*Db or use this MA*VA+ MB*VB =(MA+MB)*Vf. But where would I get V?