Question

State and prove principle of conservation of angular momentum. Explain in with example

Answer 1

The law of conservation of momentum states
that the total momentum of an isolated
system with no external forces is conserved.
When physicists say something is conserved
they mean that the total amount remains
constant. It can neither increase nor
decrease.
The surface area of a triangle is proportional
to the product of the base and the height.
Here the base of each triangle is r , the radial
distance, and the height is r·Δθ (where Δθ is
the angle that is swept out during the time
interval Δt )
Dividing the area by the interval of time gives
the amount of area that is swept out per unit
of time.
In the limit of Δt going to infinitisimal the
expression for the conserved quantity is
proportional to the following expression:
Where ω is the angular velocity.
So we have the following conserved
quantity: r ω
Law of conservation of angular
momentum states that the angular
momentum of a rotating system about
an axis remains constant in absence of
any external torque.

Answer 2

Answer:

The linear momentum and angular momentum of the body is given by →p=m→v and →l=→r×→p about an axis through the origin. The angular momentum →l may change with time due to a torque on the particle. ∴→l = constant, i.e. →l is conserved. ... its angular velocity will also change if there is no external torque