Question

What is meant by contact force and non-contact force, explain with the help of example.

Answer 1

Hint: By their very name we should be able to differentiate them. It is a broader perspective to categorize forces as contact or non-contact in nature. There are a number of regular forces we encounter on a daily basis we can categorize under contact or non-contact nature.

Complete step by step solution:
Let’s start with the definition of force. Force is defined as a push or pull upon an object by another object due to their interaction. Newton defined force as the amount acceleration produced on a unit mass when a push or pull is applied on it. In other words, force can be defined as the product of mass of an object and the acceleration produced after interaction with the force.
Mathematically, \[F = ma\]

We can classify forces broadly under two categories. The contact forces and non-contact forces. Let’s look at them one by one.
Contact forces:
These are those forces that result when the two interacting objects are said to be physically contacting each other. That is when the body which is applying force is placed in contact with the body on which the force is being applied. These may or may not be natural forces. There are various types of contact forces, applied force, normal reaction, tensional force etc.
Examples of contact forces are: a horse pulling a cart, the sumo wrestlers, wrestling, pushing a log etc.

Non-contact forces:
These are those types of forces that result even when the two interacting objects are not in physical contact with each other. They exert force upon one other from a distance long or short, but abstaining physical contact. Most of the natural forces are contact forces. These can be electrostatic forces, magnetic interactions, gravitational forces etc.
Examples of non-contact forces are: earth orbiting around the sun due to their gravitational interaction, electrons orbiting around the nucleus, a magnet pulling a iron rod when in its proximity etc.

Note: Defining forces as contact or non-contact simply means that the interacting objects are either in contact with each other or not. We might get asked MCQ type questions asking if gravitational force is a contact force, if a person pulling a weight using a pulley is a non-contact force, like these. Analyse every question well before jumping into the answer.