What about inelastic collisions?

In case of collision, if the total kinetic energy before the collision and the total kinetic energy after the collision between the objects participating in the collision are not equal or less, then the collision is called an inelastic collision. For example, if we say, two cars moving with a kinetic energy of 100 joules and 150 joules collide. Now after the collision, their kinetic energies are 80 joules and 120 joules. Here the total kinetic energy before the collision is 250 joules but after the collision, the energy is 200 joules. That is, 50 joules of energy have been wasted. Since there is no conservation of kinetic energy between them, we call this collision an inelastic collision.

All the collisions in our real life are inelastic. Because when any collision occurs, there is sound, heat, etc. generated. And these are the powers. And this power is generated from the kinetic energy of the two cars. Here some of the car’s kinetic energy is consumed. So the kinetic energy after the collision is less than the previous kinetic energy.