Q: A solid sphere rolls without slipping on a rough horizontal floor, moving with a speed $ \boldsymbol{v} . $ It makes an elastic collision with a smooth vertical wall. After impact, This question has multiple correct options

it will move with a speed $ v $ initially.. Because the wall is smooth, it exerts no tangential impulse, so the sphere’s spin is unchanged during impact. For an elastic collision with a fixed wall, the center-of-mass speed immediately after impact has the same magnitude as before, so it moves away with speed v initially.

Q: The moment of inertia of a flywheel is $ 0.2 k g m^{2} $ which is initially stationary. constant external torque $ 5 N m $ acts on the wheel. The work done by this torque during 10 sec is:

$ 1250 J $. A constant torque produces a constant angular acceleration, so the wheel’s angular displacement in 10 s can be found from rotational motion equations. The work done by the torque is then W = τθ, which gives 1250 J.

Question 1

A solid sphere rolls without slipping on a rough horizontal floor, moving with a speed $ \boldsymbol{v} . $ It makes an elastic collision with a smooth vertical wall. After impact, This question has multiple correct options

Accepted Answer

it will move with a speed $ v $ initially.. Because the wall is smooth, it exerts no tangential impulse, so the sphere’s spin is unchanged during impact. For an elastic collision with a fixed wall, the center-of-mass speed immediately after impact has the same magnitude as before, so it moves away with speed v initially.

Question 2

The moment of inertia of a flywheel is $ 0.2 k g m^{2} $ which is initially stationary. constant external torque $ 5 N m $ acts on the wheel. The work done by this torque during 10 sec is:

Accepted Answer

$ 1250 J $. A constant torque produces a constant angular acceleration, so the wheel’s angular displacement in 10 s can be found from rotational motion equations. The work done by the torque is then W = τθ, which gives 1250 J.

Question 3

An object is allowed to roll down an inclined plane starting from rest (consider the object to be uniform and having same mass) then object having largest rotational momentum is (if rotated with same angular momentum)

Accepted Answer

solid sphere. For rolling from rest down the same incline, the object with the smallest moment of inertia gains the greatest angular speed. Since rotational momentum is angular momentum, L = I\omega, the shape that rolls fastest can have the largest rotational momentum; among the listed uniform bodies, the solid sphere has the smallest I.

Question 4

Moment of momentum is called:

Accepted Answer

Angular momentum. Moment of momentum is the quantity that measures rotational motion, which is called angular momentum. Torque and impulse are related to changing momentum, not the momentum itself.

NEET Physics: Rotational Motion questions with solutions

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