# What Is Force? Types Of Forces And Their Nature

Force : types of forces

Greek philosopher and scientist Aristotle believed that the motion of a body is caused by something external and even to stop that motion, something external is required.

We have given this something special a name: Force. We all have heard this word somewhere. In fact, it is so commonly used that we use it in conversing in everyday life. In physics, we say that pushing or pulling requires force. When we are pushing a body we are applying force away from ourselves, and when we are pulling a body we are applying force towards ourselves. Not only us, even non-living things exert forces. Earth, for instance, exerts a gravitational force on all the objects present on Earth.

Roughly we can say that force is an interaction between two objects. Note that this is not the exact definition of force. The SI unit of force is Newton, and force is a vector quantity, i.e. it has both magnitude and direction.

## Types of forces:

In our day to day life we observe various types of forces around us. Some of these common types of forces are:

• Gravitational force: In general, this is a force which exists because of the attraction between two bodies by the virtue of their masses. It is given by:

$F$ = $G \frac{m_{1}m_{2}}{r^{2}}$

where,

G = Universal constant having value of $6.674×10^{−11} Nm^2/kg^2$

$m_1, m_2$ are the masses of the bodies

r is the distance between them

• Electromagnetic force: It is a force exerted by two charged particles on each other. Friction and Tension are the common examples of electromagnetic force.
• Nuclear force: This is also known as strong force or nuclear interactions. Every atom has protons and neutrons. Nuclear force is responsible for binding neutrons and protons in an atom together. This force is many magnitudes larger than any force discussed here but it has a very short range of influence after which other forces mentioned here become dominating.
• Weak force: Sometimes a neutron changes itself to a proton, and emits an electron, and a particle called antineutrino. This process is called beta decay. Weak forces are responsible for such kind of decays and interactions. Weak force is actually a force of attraction that work at an even shorter range of 0.1 percent of the diameter of a proton. The forces which are responsible for such a process differ from gravitational, electromagnetic, or nuclear forces. Such forces are called weak forces.

A video describing the nature and importance of the friction force is given below.

#### Practise This Question

State true and false.
Stars appear to twinkle when seen from the Moon.