**Dynamics of Rotational Motion about a Fixed Axis MCQs and Answers** will be useful for various entrance exam like NEET, AIIMS, JEE. It includes an extensive section of physics and chemistry. These chapter covers each and every topic of System of Particles and Rotational Motion and more. It also contains chapter-wise MCQs with hints and options to make your preparation easy. We also published * System Of Particles And Rotational Motion MCQs and Answers* which are most important and relevant topic to your upcoming examination.

## Dynamics of Rotational Motion about a Fixed Axis MCQs

**1. A disc of radius 10cm is rotating about the central axis perpendicular to its plane. A force of 5N acts on it tangentially. The disc was initially at rest. Calculate the value of power supplied by the force when the disc has rotated by 30°.The mass of the disc is 2kg.**

a) 1.28W

b) 1.8W

c) 3.9W

d) 2.63W

**Answer: **b

**2. A rod is rotating about one end. If a force F1 acting on the other end produces a torque T & supplies power P, find the value of force F2 that will produce the same amount of power when it acts at the midpoint of the rod. Assume that all forces are perpendicular to the axis of rotation & axis of rod. The rod starts from rest.**

a) = F1

b) > F1

c) < F1

d) No force acting at any other point will produce the same power

**Answer: **b

**3. A rigid body is rotating about an axis. One force F**_{1}** acts on the body such that its vector passes through the axis of rotation. Another force F**_{2}** acts on it such that it is perpendicular**** to the axis of rotation and at a point 5cm from the axis. This force F**_{2}** is perpendicular to the radius vector at its point of application. Find the net torque on the body. Let F**_{1}** = 10N & F**_{2}**= 5N.**

_{1}

_{2}

_{2}

_{1}

_{2}

a) 0

b) 10.25Nm

c) 0.25Nm

d) 10Nm

**Answer: **c

**4. A ring of radius 7cm is rotating about the central axis perpendicular to its plane. A force acts on it, tangentially, such that it does a work of 10J in a complete rotation. Find the value of that force. `**

a) 0.5/7? N

b) 35? N

c) 500/7? N

d) 0.7 N

**Answer: **c