Newton's law of motion look the same to all observers in inertial frames of reference.

It is equally true that if momentum is conserved in one inertial reference frame, it is conserved in all inertial frames.

This java applet apply the above concept to one dimensional collision problem.

Two circular objects are confined to move in one diminution (between two

Press

- Circular objects will move with some predefined velocity (yellow arrow).

Click the mouse button to

While the animation is suspended:

- Click near the arrow of the velocity vector and drag it left/right to

Click at the center of the circle to

Click within the circle to

- Click right mouse button to increase mass by one unit.

Click left mouse button to decrease mass one unit.

Press

- eta is the

eta = | relative velocity just after collision/relative velocity just before collision |

for elastic collision eta=1., for perfectly inelastic collision eta=0.

You can select

lab is a laboratory inertial frame.

and CM are frame of reference with respect to left circular object , right circular object and center of mass for and .

The velocity of two objects after collision ()can be calculated from velocity before collisions () and mass of two objects ().

From conservation of momentum ,

and conservation of energy

So

and , which means

So

i.e. The equation need to be solved are

and

The result is

and

where

It means that and

or and where ...etc.

From the point of center of mass coordinate system: both particles bounce back with the same speed (relative to center of mass).

-*-

You are welcomed to check out collision in 2 dimension.