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A body is rotating with angular velocity $30 rad s^{- 1}$ . If its kinetic energy is $360 J,$ then its moment of inertia is

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Important Questions on Rotation

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JEE Main

IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 15

A pulley of radius

2 m

is rotating about its axis by a force

F = (20 t - 5 t^{2}) N

(where

t

is measured in second) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is

10 kg m^{2}

, the number of rotations made by the pulley before its direction of motion, if reserved, is

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 16

A mass

m

hangs with the help of a string wrapped around a pulley on a frictionless bearing. The pulley has mass

m

and radius

R

. Assuming pulley to be a perfect uniform circular disc, the acceleration of the mass

m

, if the string does not slip on the pulley, is

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 17

A ring starts to roll down the inclined plane of height

h

without slipping. The velocity with which it reaches the ground is

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 18

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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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 19

A solid sphere of mass

m

rolls down an inclined plane without slipping, starting from rest at the top of an inclined plane. The linear speed of the sphere at the bottom of the inclined plane is

v

. The kinetic energy of the sphere at the bottom is

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 20

A binary star consists of two stars,

A

(mass 2.2 M_{S})

and

B

(mass 11 M_{S}),

where

M_{S}

is the mass of the sun. They are separated by distance

d

and are rotating about their centre of mass, which is stationary. The ratio of the total angular momentum of the binary star to the angular momentum of the star

B

about the centre of mass is

EASY

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IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 21

From a circular ring of mass

M

and radius

R,

an arc corresponding to a

90 °

sector is removed. The moment of inertia of the remaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is

k

times

M R^{2} .

Then, the value of

k

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IMPORTANT

Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 9 - Rotation>Objective Problems>Q 22

A wheel of moment of inertia

2.5 kg m^{2}

has an initial angular velocity of

40 rad s^{- 1} .

A constant torque of

10 N m

acts on the wheel. The time during which the wheel is accelerated to

60 rad s^{- 1}

A body is rotating with angular velocity 30 rad s-1. If its kinetic energy is 360 J, then its moment of inertia is

Important Questions on Rotation

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A body is rotating with angular velocity $30 rad s^{- 1}$ . If its kinetic energy is $360 J,$ then its moment of inertia is