1. The problem statement, all variables and given/known data In 1986, four high school students built an electric car that could reach a speed of 106 km/h. The mass of the car was just 60.0 kg. Imagine two of these cars performing in a stunt show. One car travels east with a speed of 106.0 km/h and the other travels west with a speed of 75.0 km/h. If each car is driven by a person with mass of 50.0 kg, how much kinetic energy is dissipated in a head on, perfectly inelastic collision? 2. Relevant equations I used these three equations: m1*v1i+m2*v2i=(m1+m2)vf KEi=1/2*m1*v1i^2+1/2*m2*v2i^2 KEf=1/2*(m1+m2)vf^2 KE=KEi-KEf 3. The attempt at a solution I've tried many attempts, but I think this one is most relevant... m1*v1i+m2*v2i=(m1+m2)vf (110kg)*(29.4m/s)+(110kg)*(-20.8m/s)=(220kg)vf vf=4.3m/s KEi=1/2*m1*v1i^2+1/2*m2*v2i^2 KEi=1/2*110kg*29.4m/s^2+1/2*110kg*-20.8^2 KEi=71335J KEf=1/2*(m1+m2)vf^2 KEf=1/2*(220)4.3^2 KEf=2033.9J KE=KEi-KEf KE=71335-2033.9 KE=69301.1J KE=69300 Joules I think that I used all the right equations, but the answer is wrong. Any help is most appreciated. Thanks.