These are self-adjusting forces developed by the other bodies, which come in contact with body under consideration. When two bodies come in contact, both apply equal and opposite force on each other. If the contact surface is smooth, the force will be in the normal direction of surface of contact. This is not true, if friction is present.
For example, consider the frictionless contact of the following bodies:
• One ball kept on the other ball . In this case the contact forces will be along common normal.
| Equation of equilibrium |
In the previous example, the body is balanced by three forces, string tension T , weight of the body W and reaction R . These are shown in Fig. 2. Applying Lami's theorem,
Giving |
