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Physics XI Notes for Physics Notes

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Angular Momentum

The measure of the quantity of motion possessed by a body in rotational motion is called angular momentum.

Definition
The angular momentum of a body about an axis is the product of its linear momentum and the perpendicular distance of the body from the axis.
In other words
The angular momentum of a body is equal to cross product of its
linear momentum and the vector distance from the axis of rotation.

Mathematical representation
If a body of mass “m” is moving in a circle or radius radius
with velocity velocity
the linear momentum of body body
is the angular momentum of the body is given by:

image1

Putting the value of image2

image3

Magnitude of Angular momentum

image4

We know that m r2 is equal to moment of inertia i.e. I = m r2
Thus,

image5

Unit of angular momentum
In S.I. System unit of angular momentum is "joule.second".

Dimension of angular momentum

image6

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