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A ring a disc , a solid sphere  and a hollow sphere with thin walls , all having the same mass but different radii, start together from rest at the top of an inclined plane and roll down without slipping. Then

a)

All of them will reach the bottom of the incline together

b)

The body with the maximum radius will reach the bottom first

c)

They will reach the bottom in the order and

d)

All of them will have the same kinetic energy at the bottom of the incline



Question ID - 100612 | SaraNextGen Top Answer

A ring a disc , a solid sphere  and a hollow sphere with thin walls , all having the same mass but different radii, start together from rest at the top of an inclined plane and roll down without slipping. Then

a)

All of them will reach the bottom of the incline together

b)

The body with the maximum radius will reach the bottom first

c)

They will reach the bottom in the order and

d)

All of them will have the same kinetic energy at the bottom of the incline

1 Answer
127 votes
Answer Key / Explanation : (c,d) -

(c,d)

In rolling without slipping, no work is done against friction. Hence, loss in gravitational potential energy of a body is equal to its total kinetic energy, i.e., linear plus rotational kinetic energies

Also,

Total kinetic energy=

Where  radius of gyration

As all the bodies have the sane final total kinetic energy, their final velocities will depend upon the ratio .Bodies with the smaller value of  will have the greater  and hence will reach the bottom earlier

127 votes


127