CBSE Class 11-Physics: Rotational Motion Worksheet 2: Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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Long Answer Type Questions

Question 1:

What do you mean by the moment of force applied on a body? Write its unit and dimensional formula.

Question 2:

Define term angular acceleration. Write its unit and dimensional formula. Establish relation between angular acceleration and linear acceleration

Question 3:

What is the difference between inertia and moment of inertia? What is the physical significance of moment of inertia?

Question 4:

A body is rotating with a uniform angular velocity about an axis. Establish a formula for its kinetic energy of rotation. Define moment of inertia of the body with respect to the axis of rotation on this basis?

Question 5:

Define angular momentum and torque. Prove that the time rate of change of angular momentum is equal to the applied external torque.

Understanding Type

Question 6:

If a body is rotating is it necessarily being acted upon by an external torque?

Question 7:

Two rotating bodies A and B have same angular momentum. The moment of inertia of A is twice that of B. Find the ratio of rotational Kinetic energies of A and B.

Question 8:

Is it easier to revolve a stone by attaching it to a shorter string rather than the longer one? Why?

Numerical Based Questions

Question 9:

Suppose the race car now slows down uniformly from to in s to avoid an accident, while still traversing a circular path in radius. Find the car՚s

(a) Centripetal acceleration,

(b) Angular speed,

(c) Tangential acceleration, and

(d) Total acceleration when the speed is .

Question 10:

A businessman enters the same revolving door on the right, pushing with of force directed perpendicular to the door and from the hub, while a boy exerts a force of perpendicular to the door, to the left of the hub. Find

(a) The torques exerted by each person and

(b) The net torque on the door.

Answers to Selected Problems

Question 9:

(a)

(b)

(c)

(d)

Question 10:

(a)

(b)

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