# Angular Momentum in Physics | Definition, Formula, Symbol, Units – Rotational Motion

Angular Momentum Definition:
The moment of linear momentum is called angular momentum.

We are giving a detailed and clear sheet on all Physics Notes that are very useful to understand the Basic Physics Concepts.

## Angular Momentum in Physics | Definition, Formula, Symbol, Units – Rotational Motion

Angular Momentum Symbol:
Angular Momentum is denoted by L.

Angular Momentum Formula:
Angular momentum, L = Iω = mvr
Where,
L = angular momentum
m = mass
v = velocity
In vector form, L = I ω = r x mv

Angular Momentum Units:
SI unit is J-s

Angular Momentum Dimensional Formula:
Dimensional formula is [ML2T-1].

Torque, t = $$\frac{d \mathbf{L}}{d t}$$

Principle of Moment:
When an object is in rotational equilibrium, then algebraic sum of all torques acting on it is zero. Clockwise torques are taken negative and anti-clockwise torques are taken positive.

Conservation of Angular Momentum Equation:
If the external torque acting on a system is zero, then its angular momentum remains conserved.
If Text = 0, then L = Iω = constant ⇒ I1ω1 = I2 ω2

Torque and Angular Momentum for a System of Particles:
The rate of change of the total angular momentum of a system of particles about a point is equal to the sum of the external torques acting on the system taken about the same point.
$$\frac{d \mathbf{L}}{d t}$$ = Text

Equilibrium of Rigid Body:
A rigid body is said to be in equilibrium, if both of its linear momentum and angular momentum are not changing with time. Thus, for equilibrium body does not possess linear acceleration or angular acceleration.

Couple in Physics Meaning:
A pair of equal and opposite forces with parallel lines of action is called couple. It produces rotation without translation.

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.