Angular velocity of second hand of a clock is from Physics Syste

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 Multiple Choice QuestionsMultiple Choice Questions

221.

In the rotational motion, different particles of the body have :

  • both linear and angular velocities equal

  • linear velocities equal but different angular velocities

  • angular velocities equal but different linear velocities

  • both linear and angular velocity different


222.

The moment of inertia of a ring about one of its diameter is I. What will be its moment of inertia about a tangent parallel to the diameter?

  • 43 I

  • 2 I

  • 32 I

  • 3 I


223.

A disc, initially at rest, starts rotating about its own axis, with a constant angular acceleration of 0.2 rad/s2. The time taken by the disc to rotate by 10 rad is (in second)

  • 7.07

  • 10

  • 14.14

  • 100


224.

A disc of a siren containing 60 holes rotates at a constant speed of 360 rpm. The emitted sound is in unison with a tuning fork of frequency

  • 10 Hz

  • 360 Hz

  • 216 Hz

  • 60 Hz


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225.

A circular disc X of radius R is made from an iron plate of thickness t, and another disc Y of radius 4R is made from an iron plate of thickness t/4. Then the relation between the moments of inertia IX and IY is

  • IY = 321X

  • IY = 161X

  • IY = IX

  • IY = 641X


226.

The moments of inertia of two freely rotating bodies A and B are IA and IB respectively IA > IB and their angular momenta are equal. If KA and KB are their kinetic energies then

  • KA = KB

  • KA > KB

  • KA < KB

  • KA = 2 KB


227.

If the earth is treated as a sphere of radius R and mass M, its angular momentum about the axis of rotation with time period T is

  • πMR2T

  • MR2T2π

  • 2πMR2T

  • 4πMR25T


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228.

Angular velocity of second hand of a clock is

  • π30 rad/s

  • π60 rad/s

  • π15 rad/s

  • π2 rad/s


A.

π30 rad/s

Second hand of a clock turns through an angle 2 π in 1 min (= 60 s)

∴ angular velocity ω = 2π60

                              = π30 rad/s


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229.

Sphere, disc and ring are allowed to roll down on an inclined plane from its top, then order in which they reach at the bottom will be

  • ring, disc, sphere

  • sphere, disc, ring

  • disc, ring, sphere

  • sphere, ring, disc


230.

If we made half the radius of earth, then duration of day will become

  • 6 h

  • 12 h

  • 24 h

  • 3 h


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