A car moving with an initial speed v collides with a second stationary car that is 52.9 percent as massive. After the collision the first car moves in the same direction as before with a speed that is 31.8 percent of the original speed. Calculate the final speed of the second car. Give your answer in units of the initial speed (i.e. as a fraction of v).
The Attempt at a Solution
I've attempted this solution using the conservation of momentum and the conservation of energy. I seem to get different answer with both though. I don't understand why I can't use the conservation of energy law to figure out this problem instead of using the conservation of momentum. Help is much appreciated