EASY
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A wheel starts from rest has an angular acceleration that is given by α=6t2. The angle it turns in time t is given as:

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Important Questions on Rotational Mechanics

HARD
A table has a heavy circular top of radius 1 m and mass 20 kg placed on four light (considered massless) legs placed symmetrically on its circumference. The maximum mass that can be kept anywhere on the table without toppling it is close to
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A thin uniform rectangular plate of mass 2 kg is placed in X-Y plane as shown in the figure. The moment of inertia about x-axis is Ix=0.2 kg m2 and the moment of inertia about y - axis is Iy=0.3 kg m2. The radius of gyration of the plate about the axis passing through O and perpendicular to the plane of the plate is

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EASY
The moment of inertia of a body about a given axis is 12 kg m2. Initially the body is at rest. In order to produce a rotational kinetic energy of 15000 J, an angular acceleration of 10 rad s-2 must be applied about that axis for a duration of________.
EASY
The inductance in a coil plays the same role as
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A circular disc of radius b has a hole of radius a at its centre(see figure). If the mass per unit area of the disc varies as σ0r then, the radius of gyration of the disc about its axis passing through the center is 
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EASY
Moment of inertia of an object does not depend upon
EASY
A long slender rod is welded to a thin circular disc of diameter 0.5 m at a point on its circumference. The rod is in the same plane as that of the disc and forms a tangent to the disc. The radius of gyration of the disc about the rod (in m) is
MEDIUM
A body of mass 5 kg acquires an angular acceleration of 10 rad s-2 by an applied torque of 2 N m. Find its radius of gyration.
MEDIUM
The radius of gyration of a uniform rod of length l, about an axis passing through a point l4 away from the centre of the rod, and perpendicular to it, is:
MEDIUM

An massless equilateral triangle EFG of side 'a' (As shown in figure) has three particles of mass m situated at its vertices. The moment of inertia of the system about the line EX perpendicular to EG in the plane of EFG is N20ma2 where N is an integer. The value of N is ___________ .

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HARD
A uniform thin bar of mass 6 kg and length 2.4 meter is bent to make an equilateral hexagon. The moment of inertia about an axis passing through the centre of mass and perpendicular to the plane of hexagon is ___________ ×10-1 kg m2.
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
EASY

Four equal masses, m each are placed at the corners of a square of length l as shown in the figure. The moment of inertia of the system about an axis passing through A and parallel to DB would be :

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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 uniform wire of mass M and length L. It is bent into a semicircle. Its moment of inertia about a line perpendicular to the plane of the wire passing through the centre is :
EASY

A wheel of mass 10 kg has moment of inertia equal to 0.1 kg m2. Then its radius of gyration equals      

MEDIUM
Four spheres each of diameter ' 2 a ' and mass ' m ' are placed in a way that their centers lie on the four cormers of a square of side b'. Moment of inertia of the system about an axis along one of the sides of the square is
MEDIUM

ABC is a plane lamina of the shape of an equilateral triangle. D, E are mid-points of AB, AC and G is the centroid of the lamina. Moment of inertia of the lamina about an axis passing through G and perpendicular to the plane ABC is I0. If part ADE is removed, the moment of inertia of the remaining part about the same axis is NI016 where N is an integer. Value of N 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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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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