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A child is standing with folded hands at...

A child is standing with folded hands at the center of a platform rotating about its central axis. The kinetic energy of the system is `K`. The child now stretches his arms so that the moment of inertia of the system doubles. The kinetic energy of the system now is

A

2K

B

K/2

C

4K

D

K/4

Text Solution

Verified by Experts

The correct Answer is:
B
`K.E = (L^(2))/(2I)`
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NARAYNA-SYSTEM OF PARTICLES AND ROTATIONAL MOTION -EXERCISE - I(H.W)
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  2. A mass is whirled in a circular path with a constant angular velocity ...

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  3. If a uniform solid sphere of diameter 0.2 m and mass 10 kg is rotated ...

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  4. A child is standing with folded hands at the center of a platform rota...

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  5. A constant torque acting on a uniform circular disc changes its angul...

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  6. If the mass of earth and radius suddenly become 2 times and 1//4th of ...

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  7. A uniform circular disc of radius R is rotating about its own axis wit...

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  8. A ballet dancer spins about a vertical axis at 60 rpm with his arms cl...

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  9. A metallic circular wheel is rotating about its own axis without frict...

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  10. A wheel at rest has M.I. 2/(pi^2) kgm^2. It is rotated by a 60W motor ...

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  11. The shaft of a motor is making 1260rpm. The torque supplied by the mot...

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  12. A thin ring of mass 1kg and radius 1m is rolling at a speed of 1ms^(-1...

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  13. A uniform thin rod of length l is suspended from one of its ends and i...

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  14. If a sphere of mass 2kg and diameter 10cm is rolling at speed of 5ms^(...

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  15. A solid sphere and a solid cylinder having the same mass and radius, r...

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  16. A solid cylinder of mass M and radius R rolls down an inclined plane o...

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  17. When a solid sphere is rolling along level surface the percentage of i...

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  18. The speed of a uniform solid cylinder after rolling down an inclined p...

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  19. A ring is allowed to roll down on an incline of 1 in 10 without slippi...

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  20. A solid sphere and a spherical shell roll down an incline from rest fr...

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