In physics we study motion (change in position). At the same time, we try to discover physical quantities, which do not change in a physical process. The laws of momentum and energy conservation are typical examples. In this section we shall apply these laws to a commonly encountered phenomena, namely collisions. Several games such as billiards, marbles or carrom involve collisions. We shall study the collision of two masses in an idealised form.
Consider two masses m1 and m2. The particle m1 is moving with speed v1i . The subscript i implying initial. We can consider m2 to be at rest. No loss of generality is involved in making such a selection. In this situation the mass m1 collides with the stationary mass m2 and this is depicted in Fig. 10.
The masses m1 and m2 fly-off in different directions. We shall see that there are relationships, which connect the masses, the velocities and the angles.