The angular momentum of a rotating body changes from Ao to 4

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 Multiple Choice QuestionsMultiple Choice Questions

131.

A solid cylinder is attached to a horizontal massless spring as shown in the figure. If the cylinder rolls without slipping, the time period of oscillation of the cylinder is

  • 2πxg

  • 2π2M3K

  • 2π3M8K

  • 2π3M2K


132.

The moment of inertia of a body about a given axis 1.2 kgm2Initially the body is at rest. In order to produce a rotational kinetic energy of 1500 J and angular acceleration of 25 rad/s2 must be applied about the axis for a duration of

  • 10s

  • 8s

  • 2s

  • 4s


133.

Five particles of mass 2 kg are attached to the rim of a circular disc of radius 0.1 m and negligible mass. Moment of inertia of the system about the axis passing through the centre of the disc and perpendicular to its plane is

  • 1 kg m2

  • 0.1 kg m2

  • 2 kg m2

  • 0.2 kg m2


134.

A particle is kept at rest at the top of a sphere of diameter 42 m. When disturbed slightly, it slides down. At what height h from the bottom, the particle will leave the sphere?

  • 14 m

  • 28 m

  • 35 m

  • 7 m


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135.

The angular momentum of a rotating body changes from Ao to 4Ao in 4 minutes. The torque acting on the body is:

  • 3/4 Ao

  • 4Ao

  • 3Ao

  • 3/2Ao


A.

3/4 Ao

Torque is the time rate of total angular momentum of a system of particles.

Torque T =dLdt =4Ao -Ao4             =3Ao4


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136.

If a spherical ball rolls on a table without slipping the friction of its total energy associated with rotational energy is :

  • 3/5

  • 2/7

  • 2/5

  • 3/7


137.

The equation of stationary wave along a stretched string is given by y = 5 sin πx3 cos 40πt where, x and y are in cm and t in second. The separation between two adjacent nodes is :

  • 1.5 cm

  • 3 cm

  • 6 cm

  • 4 cm


138.

If the angle between the vectors A and B is θ, the value of the product B × A. A is equal to

  • BA2 cosθ

  • BA2 sinθ

  • BA2 sinθ cosθ

  • zero


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139.

The moment of inertia of a uniform circular disc of radius R and mass M about an axis passing from the edge of the disc and normal to the disc is

  • 12 MR2

  • MR2

  • 72 MR2

  • 32 MR2


140.

A force of -F k^ acts on O, the origin of the coordinate systems. The torque about the point (1, -1 ) is

  • F i^ - j^

  • - F i^ + j^

  • F i^ + j^ 

  • -F i^ - j^


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