Change in Kinetic Energy in a Inelastic collision

[DNSalehi]

Just had a general question involving the change in Kinetic Energy in a Inelastic collision between 2 cars going towards each other at equal velocity.

ΔK = K - K_o

However for the final K, is the mass the combined mass of both cars since they are now moving together, or is it still the same mass as before the collision?

 

[PhanthomJay]

After using conservation of momentum to determine the speed of the cars after the collision, the change in K of the system is found by comparing the combined energy of both cars before and after the collision. If you are concerned about the change in K of each car separately, then compare each car's change in K separately for each car. The sum total of each car's change in K will be equal to the change in K of the system.