# What is Torque in Physics? | Definition, Formula, Symbol, Units – Rotational Motion

Torque Definition Physics:
Torque is a measure of how much a force acting on an object causes that object to rotate. The object rotates about an axis, which we will call the pivot point, and will label ‘O’. We will call the force ‘F’.

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## What is Torque in Physics? | Definition, Formula, Symbol, Units – Rotational Motion

Torque or moment of a force about the axis of rotation

τ = r x F = rF sin θ $$\hat{\mathbf{n}}$$

It is a vector quantity. It is also known as moment of force or couple.

If the nature of the force is to rotate the object clockwise, then torque is called negative torque and if rotate the object anti-clockwise, then it is called positive torque.

Torque Units:
SI unit is N-m

Torque Symbol:
τ

Torque Dimensional Formula:
Dimensional formula is [ML2T-2].

Torque in Rotational Motion:
In rotational motion, torque, τ = I α
where,
α is angular acceleration
I is moment of inertia.

Rotational Motion:
In this portion, we will learn about the rotational motion of the objects. A body moves completely in rotational motion when each particle of the body moves in a circle about a single line. When a force is applied on a body about an axis it causes a rotational motion. The force applied here is called the torque. The axis of the rotation usually goes through the body. Also, learn the two theorems such as parallel axes and perpendicular theorem explained with respect to rotational motion of objects.