Q132 / 160 · TS EAMCET 2021 (05 Aug Shift 1) · Physics

Three bodies a ring, a solid cylinder and a solid sphere roll down an inclined plane without slipping. They start from rest. Which of the bodies reaches bottom of plane with minimum velocity?

  • Correct answer
    A
    ring
  • B
    solid cylinder
  • C
    solid sphere
  • D
    both ring & solid sphere

Solution

Figure
Say, the radius of gyration of the body is K.
The mass is m.
The height is h.
The radius of the body is R.
According to the conservation of mechanical energy,mgh=12mv21+K2R2 or v2=2gh1+K2R2
Note: It is independent of the mass of the rolling body.
For a ring, K2=R2
So, the speed of the ring becomes,vring=2gh1+1=gh
For a solid cylinder, K2=R22
vcylinder=2gh1+12=4gh3
For a solid sphere, K2=25R2
vsphere=2gh1+25=10gh7
Among the given three bodies, the solid sphere has the greatest and the ring has the least velocity at the bottom of the inclined plane.

Hence, the correct answer is option: 'A'.

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