Class 12 physics rotational motion important question for exam .NEB very very important question

 Here’s a list of important Class 12 Physics questions from the chapter “Rotational Motion” based on the NEB (National Examination Board - Nepal) syllabus. The questions are divided into short questions, long questions, and numerical problems. This list is helpful for final exam preparation.

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📘 Important Short Questions (VSA/SAQ)

1. What is the difference between rotational and translational motion?

2. Define moment of inertia. What factors affect it?

3. What is radius of gyration?

4. State and explain parallel axis theorem.

5. State and explain perpendicular axis theorem.

6. Define torque. What is its SI unit?

7..What do you mean by angular momentum? Give its formula and unit..

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8. State the law of conservation of angular momentum with one example.

9. Why a tightrope walker carries a long pole?

10. Why are wheels made heavier at the rim?

11. Give the condition for pure rolling.

12. What is the relation between linear velocity and angular velocity in rolling?

13. Why is the angular momentum conserved when a skater pulls in her arms?

14. Why is it difficult to open a door by pushing it near the hinges?

5. What is the dimensional formula of moment of inertia?

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🧠 Important Long Questions (LAQ)

1. Derive the relation between torque and angular acceleration.

2. Derive the expression for kinetic energy of a rotating body.

3. Prove that for a thin ring about its central axis.

4. State and prove conservation of angular momentum.

5. Derive the expression for acceleration of a body rolling down an inclined plane.

6. Compare linear motion and rotational motion (at least 5 points).

7. Derive expression for moment of inertia of

(a  Solid sphere

(b) Solid cylinder

(c) Thin rod about an axis perpendicular and through its center

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🔢 Important Numericals

1. Moment of Inertia of Rod

A rod of mass 2 kg and length 1.5 m is rotated about an axis perpendicular to its length and through its center. Calculate its moment of inertia.

2. Torque Calculation

A force of 20 N is applied at the end of a 0.5 m long wrench at an angle of 90°. Calculate the torque.

3. Rolling Motion

A solid sphere rolls down a smooth inclined plane of height 2 m. Find its linear velocity at the bottom.

4. Angular Momentum

A disc of mass 5 kg and radius 0.5 m rotates at 10 rad/s. Find its angular momentum.

5. Conservation of Angular Momentum

A girl sitting on a rotating stool extends her arms to increase her moment of inertia from 2 kg·m² to 3 kg·m². If her initial angular velocity was 4 rad/s, find her final angular velocity.

6. Kinetic Energy of Rotating Body

A flywheel has a moment of inertia of 4 kg·m² and is rotating at 3 rad/s. Calculate its rotational kinetic energy.

7. Parallel Axis Theorem

A uniform rod of length 2 m and mass 5 kg has its moment of inertia about its center as . Find its moment of inertia about one end.

Thanks 👍 for watching..  

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u want model answers or step-by-step solutions to any of these, let me know which part you'd like to start with (short/long/numericals).