# When a moving object collides with a stationary object of identical mass, the stationary object encounters the greater collision force. Is that true or false? Why?

##### 1 Answer

In an ideal case of "head-to-head" elastic collision of material points occurring during a relatively short period of time the statement is false.

One force, acting on previously moving object, slows it down from initial velocity

In practice we have to consider many factors here. The first one is elastic or inelastic collision takes place. If it's inelastic, the law of conservation of kinetic energy is no longer applicable since part of this energy is converted into internal energy of molecules of both colliding objects and results in their heating.

The amount of energy thus converted into heat significantly affects the force causing the movement of the stationary object that depends very much on the degree of elasticity and cannot be quantified without any assumption about objects, the material they are made of, shape etc.

Let's consider a simple case of almost elastic "head-to-head" collision (there are no absolutely elastic collisions) of one object of mass

Cancelling the mass

Therefore, the solution to this system of two equations with two unknowns velocities

The other algebraically correct solution

Since the previously moving object decelerates from