1. The problem statement, all variables and given/known data I'm supposed to find the potential energy at the start of a system for a vehicle given that the mass is 4000kg, the total distance traveled is 800m, and 3/4 of the total energy is lost to heat and friction by the end of the distance traveled (it's assumed that the vehicle starts from rest). Now, I know I can easily solve for a variable, but given this information I'm under the impression that I need to get a numerical answer. It's frustrating because I feel like I am not taking something into account. 2. Relevant equations PE = mgh 3. The attempt at a solution I've come up with really just substitution for the variables, so: PE = 4500kg*9.8m/s^2*h.