# 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)