1. The problem statement, all variables and given/known data Jennifer (mass 60.0kg) is standing at the left end of a 14.0m long 538.0kg cart that has frictionless wheels and rolls on a frictionless track. Initially both Jennifer and the cart are at rest. Suddenly, Jennifer starts running along the cart at a speed of 5.10m/s relative to the cart. How far will Jennifer have run relative to the ground when she reaches the right end of the cart? 2. Relevant equations momentum = mv p is momentum 3. The attempt at a solution Pi = 0 so 60*5.1 = 538v v=0.568m/s velocity of cart 14m of cart takes her t(5.668m/s) = 14 t=2.46s I'm confused about this relativity, do i use velocity of 5.1 when calculating conservation of momentum ? or is is speed relative to ground? How do i get to a number in meters relative to the ground that she ran?