1. The problem statement, all variables and given/known data Two remote control cars with masses of 1.11 kilograms and 1.81 kilograms travel toward each other at speeds of 8.75 meters per second and 3.39 meters per second, respectively. The cars collide head-on, and the less massive car recoils with a speed of 2.99 meters per second. How much kinetic energy was lost in the collision? 2. Relevant equations no idea 3. The attempt at a solution I don't really understand how to start.... I was thinking we could calculate the total momentum of the system then calculate the ideal final velocity of the less massive cart then calculate the difference? Would you fine the total momentum of the system... thus (1.11 kg)(8.75 m)+(1.81 kg)(- 3.39m) = 3.5766 kg * m /s then divide that by 1.11 kg to find the ideal velocity of the smaller cart.... or 3.22216ish m/s.... then get the kinetic energy of that which will be 1/2(1.11)(3.2216)^2 = 5.762192 J , then find the kinetic energy of the kinetic energy of it actually, or 1/2(1.11)(2.99)^2 = 4.961755 then subtract 5.7621 - 4.9617 = .800 J ?