A push or pull exerted by an object on another is a force. Force arises due to the interaction between at least two objects.
Force has both Magnitude and Direction. Force applied on an object in the same direction add to one another. If the two forces act in the opposite direction on an object, the net force acting on it is the difference between the two forces. In general, more than one force may be acting on an object at any given point. However, a force acting on an object is always the mean net force acting on it.
Two friends pushing a heavy load (a) in the same direction and (b) in the opposite direction. A Force can Change the State of Motion. A change in the speed of an object or the direction of its motion or both implies a change in its state of motion. Force acting on an object may bring a change in its state of motion or a change in its shape. Ex: A rubber band suspended from a hook/nail fixed on a wall. By hanging a weight or by pulling its free end.

Types of Forces

1. Contact Forces

The forces act on a body when the source of force is in actual contact with the body. (i) Muscular Force: The force exerted by the muscles of the body. (ii) Mechanical Force: The force produced by a machine. (iii) Frictional Force: The force that opposes the motion of an object.

2. Non-Contact Forces

Forces that do not involve physical contact between two bodies on which they act. (i) Magnetic Force: A magnet exerts a non-contact force on objects made of iron, steel, cobalt or nickel. (ii) Electrostatic Force: The force which results due to repulsion of similar charges or attraction of opposite charges. (iii) Gravitational Forces: The force that exists between any two masses because of their mass.


The force that acts on a surface in a direction perpendicular to it, is known as thrust.


The force acting on per unit area, applied to an object in the direction perpendicular to the surface is called pressure. Liquids exert pressure on the walls of the container in which they are kept. Gases exert pressure in all directions.

Atmospheric Pressure

The pressure exerted by atmospheric air around us is known as atmospheric pressure.

Table of Contents