What is force?
Force is strength or energy applied towards any object for physical action or any movement. A force is a push or pull resulting due to the interaction between two objects. Force is external and results only when there is interaction between objects.
Different types of forces and their examples
Force can be classified into two broad categories
1. Contact forces
These are those types of forces when two objects interact with each other; they have a physical contact with each other. Types of contact forces are: Frictional force; Tension force; Normal Force; Air Resistance Force, Applied Force, Spring Force.
I. Frictional force
As an object moves across a surface it causes friction. Friction force can be sliding or static. Friction depends upon the nature of the two interacting surfaces. Example: A book sliding on the table, a ball rolling on the floor.
II. Tension force
A force that is transmitted through a string, rope, cable or wire when it is pulled tightly by the object on the opposite end is a tension force. This force flows across the length of the wire or rope. Example- A cable car or climbing a mountain using a rope.
III. Normal force
This is the force exerted upon an object that is in contact with another stable object. Usually a normal force is applied horizontally between two objects in contact. Example-A book resting on a table or a person leaning on the wall.
IV. Air Resistance force
This a frictional force applied on objects when they are in air. Often the Air Resistance force opposes the movement of the object. It is noticeable for objects that travel at high speed up in the air. Example- An airplane or a parachute.
V. Applied force
A force with which an object has been pushed or pulled. Here a force is applied to an object by a person or any other object. Example- A person pushing a chair to the other side of the room
VI. Spring force
It is the force which results when a spring is stretched or compressed. A spring is a metal elastic device that returns to its original form when pulled or pressed. If the spring is stretched, spring force is attractive. If it is compressed, spring force is repulsive. Example- Trampoline, diving board etc.
2. Action at a distance forces
These types of forces happen when two interactive objects are not in physical contact with each other; yet they are able to push or pull. Types of Action at a distance forces are: Gravitational force, Electrical force and Magnetic forces.
I. Gravitational force
This is the force by which the Earth or moon or other massively huge objects attract another object towards them. All objects on the Earth experience the gravitational force, which is directed downwards towards the center of the earth. The force of gravity is always equal to the weight of the object.
II. Electrical force
It is one of the fundamental forces of the Universe. It is a force that exists between all charged particles. It is all around us. It is responsible for making our hair stand on a cold day. When the hair on the head stands and refuses to be brushed, that is static energy. It is this force which allows you to see when you turn on the lamp in a dark room.
III. Magnetic force
This is a push or pull exerted by a magnet. The force of attraction between an object and a magnet is called magnetism. All magnets have north and south poles. This force is the attraction or repulsion that arises between electrically charged particles due to their motion. Example- Iron nails when placed near a magnet.