# System of particles and rotational motion

For complete equilibrium, both these conditions must be fulfilled. A line passing through this common centre is the axis of rotation. Angular momentum can be defined as the vector product of the angular velocity of a particle and its moment of inertia.

The distances between all pairs of particles of such a body do not change. Here we neglect the friction acting during the mechanism of rotation.

The phenomenon seems simple, but did you ever wonder that with every rotation that you make the Angular momentum changes.

When we study rotational momentum in reference to a rigid body, we take it as a vector acting on a system of particles. The centre of mass of a two- particle system always lies on the line joining the two particles and is somewhere in between the particles.

Here we shall deal with angular momentum about a fixed axis. Its velocity is constant and acceleration is zero, i.

## System of particles and rotational motion class 11 notes pdf pradeep

What exactly is angular momentum? When a particle of mass m shows linear momentum p at a position r then the angular momentum with respect to its original point O is defined as the product of linear momentum and the change in position. The relation between the two is same as that of force and linear momentum. When calculating the angular momentum for any particle we need to know the relation between the moment of a force and angular momentum. As already said, in rotational motion we take angular momentum as the sum of individual angular momentums of various particles. The angular momentum discussed here, is that of a rigid body rotating about a fixed axis. It isâ€¦ the moment of inertia directly proportional to the moment of inertia none of the above Solution: C. With the help of Angular momentum in the rotation along the fixed axis, we can now understand how various acrobats and skaters manage their angular speed during their actions. Well, the reason is the changing angular momentum during the circular motion of the ballet dancer. For bodies like these, every particle experiences a velocity v which is opposed by another velocity -v that is located diametrically opposite in the circle covered during the rotation by the particle. When we study rotational momentum in reference to a rigid body, we take it as a vector acting on a system of particles.

This is due to the changing external torque and angular momentum. When calculating the angular momentum for any particle we need to know the relation between the moment of a force and angular momentum. The angular momentum of any particle rotating about a fixed axis depends on the external torque acting on that body.

With the help of Angular momentum in the rotation along the fixed axis, we can now understand how various acrobats and skaters manage their angular speed during their actions. The net force due to a couple is zero, but they exert a torque and produce rotational motion.

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