Force is a physical cause that changes or may tend to change the state of rest or the state of motion of an object. Force comes into play due to interaction of two or more objects.
Force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape.
• Combined forces -Forces applied on an object in the same direction add to one another. If the Forces acting in opposite directions on an object, the net force acting on it is the difference between two forces.
• Contact forces -The forces which act on bodies when they are in physical contact. e.g. Frictional force, Tension force as applied through strings, Force exerted during collision.
• Non Contact forces - The forces which act on bodies when they are not in physical contact e.g. Electrostatic force, Magnetic force
When a force is applied normally on the handle of a door, the door begins to rotate about an axis passing through the hinges on which the door rests. This force is called turning effect of force or moment of force or torque.
Learn about principle of moments and their applications.
When a particle moves with a constant speed in a circular path, its motion is said to be the uniform circular motion. Do you know which force is mainly responsible for keeping the particle in a circular path? It is centripetal force and it is always directed towards centre of the circle. Learn about centrifugal force and see how it effects the motion of a body.