1. The problem statement, all variables and given/known data One car has twice the mass of a second car, but only half as much kinetic energy. When both cars increase their speed by 5.7 m/s, they then have the same kinetic energy. What were the original speeds of the two cars? 2. Relevant equations KE=1/2mv^2, where KE equals kinetic energy. 3. The attempt at a solution Don't know where to start. Car 1: .5KE=(1/2)(m)(v1^2) Car 2: KE = (1/2)(.5m)(v2^2) You can set the 2 equations equal in KE when 5.7 is added to both v1 and v2, but there are still too many variables! I have been stuck on this problem for 2 hours and I am about to go crazy! Please help!