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NEET Rotational Motion: 5 practice MCQs with answers

By the PrepMatic team · Updated 9 Oct 2026 · 4 min read

Rotational Motion is where Class 11 Physics gets conceptually heavier: torque, moment of inertia and angular momentum replace force, mass and linear momentum. The five MCQs below test torque, the moment of inertia of a rod, conservation of angular momentum, rolling motion and rotational kinetic energy, at NCERT Class 11 level.

What this chapter covers in the NEET syllabus

The NMC unit is Rotational Motion, and NCERT covers it in the Class 11 chapter System of Particles and Rotational Motion. The topics are:

• Centre of mass of a system of particles and of simple rigid bodies.
• Torque, angular momentum and the relation between them.
• Conservation of angular momentum and its everyday examples.
• Moment of inertia, radius of gyration, and the parallel and perpendicular axes theorems.
• Rotational kinetic energy and the equations of rotation with constant angular acceleration.
• Rolling motion, with and without slipping.

Five practice MCQs on Rotational Motion

Question 1

A force of 20 N is applied at the end of a 0.5 m spanner, at an angle of 30° to the spanner. The torque about the nut is:

• A. 10 N m
• B. 20 N m
• C. 5 N m
• D. 8.66 N m

Question 2

The moment of inertia of a thin uniform rod of mass M and length L about an axis through its centre and perpendicular to its length is:

• A. ML²/12
• B. ML²/3
• C. ML²/2
• D. ML²/6

Question 3

A skater spinning with arms outstretched pulls her arms in, so that her moment of inertia becomes half. Her angular velocity:

• A. is halved
• B. remains unchanged
• C. becomes four times
• D. doubles

Question 4

A solid sphere rolls without slipping on a horizontal surface. The fraction of its total kinetic energy that is rotational is:

• A. 2/5
• B. 2/7
• C. 5/7
• D. 1/2

Question 5

A wheel of moment of inertia 0.5 kg m² rotates at 10 rad/s. Its rotational kinetic energy is:

• A. 5 J
• B. 50 J
• C. 25 J
• D. 250 J

Answers and explanations

1. C. Torque is τ = r F sin θ = 0.5 × 20 × sin 30° = 0.5 × 20 × 0.5 = 5 N m. Option D comes from using cos 30° instead of sin 30°, and option A from using no angle at all.
2. A. For a uniform thin rod, I = ML²/12 about the centre and ML²/3 about one end. The second value follows from the parallel axes theorem: ML²/12 + M(L/2)² = ML²/3.
3. D. No external torque acts, so angular momentum Iω is conserved. If I halves, ω must double. Her rotational kinetic energy also doubles, because KE = L²/2I, and the extra energy comes from the work she does pulling her arms in.
4. B. For a solid sphere I = (2/5)MR² and ω = v/R. Rotational KE = ½Iω² = (1/5)Mv², and translational KE = ½Mv². The total is (7/10)Mv², so the rotational fraction is (1/5)/(7/10) = 2/7.
5. C. KE = ½Iω² = ½ × 0.5 × 10² = ½ × 0.5 × 100 = 25 J. Option B forgets the half, and option D forgets to square ω.

How to prepare Rotational Motion

Most of this chapter is the linear mechanics you already know, translated. Learn the dictionary below and the rest follows.

• Memorise the standard moments of inertia: ring MR², disc ½MR², solid sphere ⅖MR², hollow sphere ⅔MR², all about the central axis through the centre. Know when to use each theorem: parallel axes for an axis shifted parallel to a central one, perpendicular axes only for flat (planar) bodies.
• Pick the right conservation law. If no external torque acts, conserve L. If only conservative forces do work, conserve energy, including the rotational part.
• Rolling problems: the contact point is instantaneously at rest when there is no slipping, so v = Rω. Write translational and rotational energy together.

Plan on two or three sessions with 20 mixed problems each, since this chapter is easy to forget unless you revisit it. For subject-level planning see the NEET Physics preparation guide, and for the unit list see the NEET syllabus.

Take a full Rotational Motion test on PrepMatic

If you have written the linear-to-rotational table in your own notes, you can upload them to PrepMatic and generate a mock from them, or take a standard topic test of about 15 questions in 30 minutes. Both are scored with NEET's negative marking. Plan limits apply, and the practice hub has other chapters.

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