Dynamics of Rotation of a Body

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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

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Four point masses (each of mass m) are arranged in the X-Y plane. The moment of inertia of this array of masses about Y-axis is 

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The dimensional formula of radius of gyration is:

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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

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Point masses 1, 2, 3 and 4 kg are lying at the points (0, 0, 0), (2, 0, 0), (0, 3, 0) and (-2, -2, 0), respectively. The moment of inertia of this system about the x-axis will be,

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

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On the marks of 20 cm and 70 cm of a light meter scale, two weights, 1 kg and 4 kg, respectively, are placed. The moment of inertia (in kg m2) about the vertical axis through the 100 cm mark will be,

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

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At shown instant a thin uniform rod AB of length L=1 m and mass m=1 kg is coincident with y-axis such that centre of rod is at origin. The velocity of end A and centre O of rod at shown instant are vA=-2i^ m s-1 and v0=10i^ m s-1 respectively. Then the kinetic energy of rod at the shown instant is:

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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 M0LT0

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

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The inductance in a coil plays the same role as

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A uniform circular disc of mass 400 g and radius 4.0 cm is rotated about one of its diameter at an angular speed of 10 rad s-1. The kinetic energy of the disc is

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The ring of radius 1 m and mass 15 kg is rotating about its diameter with angular velocity of 25rad/sec. Its kinetic energy is

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

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A body having a moment of inertia about its axis of rotation equal to 3 kg m2 is rotating with an angular velocity of 3 rad s-1. Kinetic energy of this rotating body is same as that of a body of mass 27 kg moving with a velocity v. The value of v is

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

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Energy of 1000 J is spent to increase the angular speed of a wheel from 20 rad s-1 to 30 rad s-1. Moment of inertia of the wheel in kg m2 

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A wheel of mass 10 kg and radius 0.8 m is rolling on a road with an angular speed 20rads-1 without sliding. The moment of inertia of the wheel about the axis of rotation is 1.2kgm2, then the percentage of rotational kinetic energy in the total kinetic energy of the wheel is ____________(approximately)