Dynamics of Rotation of a Body
Dynamics of Rotation of a Body: Overview
This topic covers concepts such as Moment of Inertia, Moment of Inertia of a Single Particle, Moment of Inertia of System of Particles, Radius of Gyration, Angular Momentum of a Rigid Body in Pure Rotation, etc.
Important Questions on Dynamics of Rotation of a Body
Four point masses each of mass are arranged in the plane. The moment of inertia of this array of masses about -axis is

The dimensional formula of radius of gyration is:

In the calculation of the radius of gyration, we use intensity of loadings. So whenever the distributed loading acts perpendicular to an area its intensity varies

Point masses and are lying at the points and , respectively. The moment of inertia of this system about the -axis will be,

Four similar point masses (each of mass ) are placed on the circumference of a disk of mass and radius . The moment of inertia of the system about the normal axis through the center will be,

On the marks of and of a light meter scale, two weights, and , respectively, are placed. The moment of inertia (in ) about the vertical axis through the mark will be,

A couple produces

The speed of a solid sphere after rolling down from rest without sliding on an inclined plane of vertical height h is

At shown instant a thin uniform rod of length and mass is coincident with axis such that centre of rod is at origin. The velocity of end and centre of rod at shown instant are and respectively. Then the kinetic energy of rod at the shown instant is:

These questions consists of two statements each printed as Assertion and Reason. While answering these questions you are required to choose any one of the following five responses.
Assertion: If we draw a circle around the centre of mass of a rigid body, then moment of inertia about all parallel axes passing through this circle has a constant value.
Reason: Dimensions of radius of gyration are

A closed cylindrical container is partially filled with water. As the container rotates in a horizontal plane about a perpendicular, its moment of inertia

The inductance in a coil plays the same role as

A uniform circular disc of mass and radius is rotated about one of its diameter at an angular speed of . The kinetic energy of the disc is

The ring of radius and mass is rotating about its diameter with angular velocity of . Its kinetic energy is

A couple produces,

The angular momentum of a particle describing uniform circular motion is . If its kinetic energy is halved and angular velocity doubled, its new angular momentum is

A body having a moment of inertia about its axis of rotation equal to is rotating with an angular velocity of . Kinetic energy of this rotating body is same as that of a body of mass moving with a velocity . The value of is

The rotational of a body is and its moment of inertia is . The angular momentum is

Energy of is spent to increase the angular speed of a wheel from to . Moment of inertia of the wheel in

A wheel of mass and radius is rolling on a road with an angular speed without sliding. The moment of inertia of the wheel about the axis of rotation is then the percentage of rotational kinetic energy in the total kinetic energy of the wheel is ____________(approximately)
