Rotational Motion

Dimensions of angular momentum is,

• [M¹L²T^-2]

• [M^-1L^-2T^-1]

• [M¹L²T^-1]

• [M¹L⁰T^-1]

• [M¹L⁰T^-2]

If a body is rotating about an axis, passing through its center of mass then its angular momentum is directed along its,

• Radius

• Tangent

• Circumference

• Axis of rotation

• chord

A body of M.I. of 5 kg m², rotating with an angular velocity of 6 rad/s, has the same kinetic energy as a mass of 20 kg, moving with a velocity of,

• 3 m/s

• 2 m/s

• 4 m/s

• 5 m/s

• 6 m/s

If radius of solid sphere is doubled by keeping its mass constant, then,

• I₁/I₂=1/4

• I₁/I₂=4

• I₁/I₂=3/2

• I₁/I₂=2/3

• I₁/I₂=1/5

By keeping moment of inertia of a body constant, if we double the time period, then angular momentum of body,

• Remains constant

• Becomes Half

• Doubles

• Triples

• Quadruples

The moment of inertia of a body about a given axis is 1.2 kg m². Initially, the body is at rest. In order to produce a rotating kinetic energy of 1500 joules, an angular acceleration of 25 radian/sec² must be applied about that axis for a duration of,

• 4 s

• 2 s

• 8 s

• 10 s

• 12 s

L²/2I represents,

• Rotational kinetic energy of a particle

• Potential energy of a particle

• Torque on a particle

• Power

• Momentum

For increasing the angular velocity of an object by 10%, the kinetic energy has to be increased by,

• 42%

• 20%

• 10%

• 21%

• 30%

A body having moment of inertia about its axis of rotation equal to 3 kg m² is rotating with angular velocity equal to 3 rad/s. kinetic energy of this rotating body is the same as that of a body of mass 27 kg moving with a speed of,

• 0.5 m/s

• 1.0 m/s

• 1.5 m/s

• 2.0 m/s

• 2.5 m/s

A constant torque of 31.4 N m is applied to a pivoted wheel. If the angular acceleration of the wheel is 4π rad/s², then the moment of inertia of the wheel is,

• 1.5 kg m²

• 2.5 kg m²

• 3.5 kg m²

• 4.5 kg m²

• 5.5 kg m²