# Force definition

The push or pull of a body by an object is called force on the body.

or

Force is an external influence acting on a body to change its state of motion.

## Types of Forces

### Contact Force

Force which results when there is a direct physical contact between two interacting objects is known as contact force.

### Types of Contact Forces

Muscular Force
The force which we exert by using our muscles is called as muscular force.

Friction Force
The force which resists the motion of an object over the surface of other.  The direction of friction force is always opposite to the direction of the motion relative to the surface.

Normal Force
The friction force, on an object, which acts perpendicular to the surface of  its plane is called as Normal Force.

Tension
Tension is a pulling force acting on a object by means of a string against the gravitational force.

### Field Force

The force which occurs without any physical contact is known as force at a distance or field force.

Field is region of imaginary lines around an object. When an other body is placed in this region, it will experience the force. The greater the density of these imaginary lines, the stronger the forces in that region.

### Types of Field Forces

Magnetic Force
Magnetic force is a field force responsible for attraction of like poles and repulsion of unlike poles.

Electrostatic Force
Force exerted by a charged body on another charged body is known electrostatic force. This force is due to electric field from the charge.

Gravitational Force
The force of attraction that exists between any two masses n the universe is known as Gravitational force. This force is due to electric field from the charge. Gravitational force is also non contact force and hence it is also a field force.

## Net Force

Multiple forces can act on an object simultaneously at a time. When the forces act in same direction then net force will be addition of all forces. When the forces are in opposite direction, then net force will be difference of the forces. When the Net force is zero, there is no change in state of object.

The direction of motion of the object will be in the direction of Net Force. If the Net Force acts in direction of motion, the speed of the an object moving with constant speed also increase. If the Net Force acts in a direction opposite to the motion, then it either slows down the object or brings it to rest or it may change the direct of motion.

The unit of force in SI system is Newton(N).

## Pressure

The force acting perpendicularly on unit area of a surface is called as pressure.

Pressure = Force/Area

The unit of pressure in SI system is Newton/Meter² or N/m²