EASY
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The ratio of moments of inertia of two solid spheres of same mass but densities in the ratio 1:8 is

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Important Questions on Systems of Particles and Rotational Motion

EASY
A light rod of length, l has two masses, m1 and m2 attached to its two ends. The moment of inertia of the system about an axis perpendicular to the rod and passing through the centre of mass is
MEDIUM
The moment of inertia of a thin uniform rod of length L and mass M about an axis passing through a point at a distance of L3 from one of its ends and perpendicular to the rod is
MEDIUM

A solid cube of wood of side 2a and mass M is resting on a horizontal surface as shown below.

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The cube is free to rotate about the fixed axis AB. A bullet of mass m<<M and speed v is shot horizontally at the face opposite to ABCD at a height h above the surface to impart the cube an angular speed ωc, so that the cube just topples over. Then, ωc is (Note the moment of inertia of the cube about an axis perpendicular to the face and passing through the center of mass is 2Ma33)

MEDIUM
From a circular cardboard of uniform thickness and mass M, a square disc of the maximum possible area is cut. If the moment of inertia of the square with the axis of rotation at the centre and perpendicular to the plane of the disc is Ma26, the radius of the circular cardboard is
MEDIUM
From a solid sphere of mass M and radius R, a cube of the maximum possible volume is cut. Moment of inertia of cube about an axis passing through its centre and perpendicular to one of its faces is:
MEDIUM
A Wheel of moment of inertia kg m2 is rotating about an axis passing through centre and perpendicular to its plane at a speed 60 rad s-1. Due to friction, it comes to rest in 5 min. The angular momentum of the wheel three minutes before it stops rotating is
EASY
Consider a thin uniform square sheet made of a rigid material. If its side is a , mass m and moment of inertia I about one of its diagonals, then:
MEDIUM

A mass m is supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If the string does not slip on the cylinder, with what acceleration will the mass fall on release?

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MEDIUM
From a disc of radius R and mass M , a circular hole of diameter R , whose rim passes through the centre is cut. What is the moment of inertia of the remaining part of the disc about a perpendicular axis, passing through the centre?
MEDIUM

Two identical spherical balls of mass M and radius R each are stuck on two ends of a rod of length 2R and mass M(see figure). The moment of inertia of the system about the axis passing perpendicularly through the centre of the rod is


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HARD

Which one of the following four graphs best depict the variation with x of the moment of inertia I of a uniform triangular lamina about an axis parallel to its base at a distance x from it

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EASY

Three identical spherical shells, each of mass m and radius r are placed as shown in the figure. Consider an axis XX which is touching the two shells and passing through the diameter of the third shell. The moment of inertia of the system consisting of these three spherical shells about XX axis is:

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HARD
Moment of inertia of an equilateral triangular lamina ABC, about the axis passing through its centre O and perpendicular to its plane is I0 as shown in the figure. A cavity DEF is cut out from the lamina, where D, E, F are the mid points of the sides. Moment of inertia of the remaining part of lamina about the same axis is:

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EASY
The moment of inertia of a uniform cylinder of length l and radius R about its perpendicular bisector is I. What is the ratio l/R such that the moment of inertia is minimum?
MEDIUM
A circular hole of radius R4 is made in a thin uniform disc having mass and radius R, as shown in figure. The moment of inertia of the remaining portion of the disc about an axis passing through the point O and perpendicular to the plane of the disc is-
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HARD
From a uniform circular disc of radius R and mass 9 M, a small disc of radius R3 is removed as shown in the figure. The moment of inertia of the remaining disc about an axis perpendicular to the plane of the disc and passing through centre of disc is:

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HARD

Seven identical circular planar disks, each of mass M and radius R are welded symmetrically as shown. The moment of inertia of the arrangement about the axis normal to the plane and passing through the point P is:
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MEDIUM
The moment of inertia of a solid sphere, about an axis parallel to its diameter and at a distance of x from it, is Ix. Which one of the graphs represents the variation of I(x) with x correctly?
EASY
A thin circular disk is in the xy plane as shown in the figure. The ratio of its moment of inertia about z and z' axes will be:
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MEDIUM
Let the moment of inertia of a hollow cylinder of length 30 cm (inner radius 10 cm and outer radius 20 cm), about its axis be I. The radius of a thin cylinder of the same mass such that its moment of inertia about its axis is also I, is: