*Topic: what is Force, Moment of Force, Couple, Torque in detail?*

It is a physical quantity that might cause an acceleration in mass. there are many definitions of Force are available.

Force can also be described as a push or a pull on an object.

Aristotle said

* “Anything that causes an object to undergo “unnatural motion,” said as Force”*

Isaac Newton‘s described as Force = Mass x Acceleration [*∴ F= ma ]*

Force has both magnitude and direction. so Force is a vector quantity. S.I Units for force is newton.

*What is meant by Magnitude? *

Magnitude is nothing but the Size or Quantity.

## What is force from the Newton’s Second Law?

From Newton’s second law it is stated that

*“The rate of change of momentum is directly proportional to the impressed force and takes place in the same direction in which the force acts”*

Momentum ∝ Force

and where,

Momentum = Mass x Velocity

∴Where

m = Mass of the body

a = constant acceleration

*u* = Initial velocity

*v* = Final Velocity

t = Time required to change the velocity from initial velocity to final velocity

Change in momentum = Mass x Change in Velocity

= Mass x (Final Velocity – Initial Velocity)

= m x (*v-u*)

Rate of change of momentum = m(*v-u*)/t

momentum = m.a

[∴Acceleration(a) = (*v-u*)/t]

From Newton’s second law, Force and Momentum are directly proportional to each other.

Force ∝ Momentum

F ∝ ma

F= k m a

**K** is a proportionality constant

For the unit of force, it produces a unit acceleration to the body of a unit mass

F= ma

S.I units for force is newton.

a newton is defined as the force while acting on a body of the mass of 1kg with an acceleration of 1meter/second²

1N = 1kg x 1m/s² = 1 kg-m/s²

There are some other few concepts related to the force are torque, a moment of force, couple

## Moment of force

A simple form of force that causes the body to rotate about a point is known as the moment of force

Moment of force = Force x perpendicular distance from the given point to the line of action of the force

Moment of force = F x* l*

## Torque

It is simply the product of the force acting on the body and the perpendicular distance from the given point to the line of action of the force. Torque is equivalent to a couple acting upon a body.

Torque = Force x perpendicular distance

T = F x *l*

## Couple

Two equal and opposite parallel forces acting upon a body with a different line of acting points said as a couple.

Moment of Couple = Force x Distance between the two line of action of the forces.

Moment of Couple = F x *x*

* Tags: what is force? Physics, Machine Design, work, power, torque, a moment of force, Couple, Mechanical Engineering Basics*

robert eligman says

We teach the physics kids about Newton’s 3 laws of motion.These are good applications of such laws.