# What is Centripetal Force [Class-12 Circular Motion]

Centripetal force is a force which keeps a rotating body in circular motion. Force is an important physical quantity which is used in many branches of physics like Kinetics, Electromagnetism, Mechanics, Thermodynamics and Electricity. Force is also central to Classical Physics, Quantum Physics and Relativity Physics.

## The basic facts about force, as a physical quantity, are:Basic Facts of Centripetal Force and Other Types of Forces

Name:    Force
SI Unit:  N (Newton)
Dimension:  [MLT-2]
Defining Equations: Force = Mass (m) x Acceleration (a).
Force is also time-rate of change of momentum, Force = Δ (p)/t
Type:  Vector Quantity {It is a product of Scalar (mass) and Vector {acceleration)}
Moment: Moment of Force is called Torque (τ). Couple is a set of two forces separated by an arm’s length.
Types of Forces: Real Force and Pseudo Force.
So what is centripetal force? It is a real force. And what is Centrifugal force. It is a pseudo force.

Four Fundamental Forces: All forces can be classified into these 4 basic (or fundamental) forces. The distinguishing attributes of each of these four fundamental forces are:
(a) Gravitational force: It is an attractive force, having infinite range and weakest of all forces. It obeys Inverse-Square-Law. It does not require medium to propagate. Gravitation force is due to the mass of an object. Example: Weight
(b) Electromagnetic force (EM): It is attractive as well as repulsive forces between two charged particles. Like charges repel; unlike charges attract each other. Electromagnetic force also has infinite range, but its relative strength with respect to Strong Nuclear Force is (1/137). Electromagnetic force obeys Inverse-Square Law. Example is friction.
(c) Strong Nuclear Force (SNF): As the name suggests, it is the strongest force, but has the limited range of (10-15 m). It holds proton & neutrons together in the nucleus.
(d) Weak Nuclear Force (WNF): It has a range of 10-18 m and relative strength (with respect to Strong Nuclear Force) of 10-6