A smooth sphere A is moving on a frictionless horizontal plane with angular speed ω and the centre of mass velocity u. It collides elastically and head on with an identical sphere B at rest. Neglect friction everywhere. After the collision, their angular speeds are ω(A) and ω(B) respectively. Then?

System of Particles and Rotational Motion topics include: Significance of rotational motion and inertia, translational and rotational motion, angular momentum and relation between torque and momentum. A system of particles is a body that experiences rotational motion when a torque is applied to it around an axis. This is similar to how translational motion is caused by force.  In rotational motion, every particle in a body moves in a circle that is perpendicular to the axis and has its center on the axis.  The combination of rotational and translational motion is known as rolling motion.... Show more

System of Particles and Rotational Motion topics include: Significance of rotational motion and inertia, translational and rotational motion, angular momentum and relation between torque and momentum.

A system of particles is a body that experiences rotational motion when a torque is applied to it around an axis. This is similar to how translational motion is caused by force. 
In rotational motion, every particle in a body moves in a circle that is perpendicular to the axis and has its center on the axis. 
The combination of rotational and translational motion is known as rolling motion. According to the law of conservation of angular momentum, the total angular momentum of a system of particles or rigid body is conserved if there is no external couple acting. 

Here are some other concepts related to systems of particles and rotational motion:
Center of mass: The point at which a body's entire mass is concentrated. It is also the system's balancing point. If an external force is applied at the center of mass, the body remains unaffected.
Rotational equilibrium: The vector sum of torques of all the forces acting on a body about the reference point must be zero.
Translational equilibrium: The vector sum of all the forces acting on a body must be zero.

Angular acceleration: α = (ω - ω₀) / t
Tangential velocity: v = r * ω 

Spinning a bike wheel or pushing a merry-go-round are examples of rotational dynamics. 

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