Rotational Motion is one of the most important chapters in Physics for NEET 2026 aspirants. Many direct as well as application-based questions are framed from this chapter every year. To score well, students must clearly understand the basic concepts, definitions, and formulas.
Here, we provide plagiarism-free, exam-focused notes with all the essential formulas in a simple way so that you can revise quickly and effectively.
Rotational Motion Notes for NEET 2026 | Formulas & MCQs
Key Concepts of Rotational Motion
Rigid Body
-
A rigid body is an object in which the distance between any two particles remains constant even when external forces are applied.
Rotational Motion
-
When all particles of a rigid body move in circles about a fixed axis, the body is said to be in rotational motion.
Important Quantities & Their Analogies
| Linear Motion | Rotational Motion |
|---|---|
| Displacement (x) | Angular displacement (θ) |
| Velocity (v) | Angular velocity (ω) |
| Acceleration (a) | Angular acceleration (α) |
| Force (F) | Torque (τ) |
| Mass (m) | Moment of inertia (I) |
| Linear momentum (p = mv) | Angular momentum (L = Iω) |
| Kinetic Energy (½mv²) | Rotational KE (½Iω²) |
Formulas – Must Remember for NEET
Angular Motion
-
Angular velocity: ω = dθ/dt
-
Angular acceleration: α = dω/dt
-
Relation with linear velocity: v = rω
-
Relation with linear acceleration: a = rα
Torque & Moment of Inertia
-
Torque: τ = r × F = rFsinθ
-
Moment of inertia: I = Σmr²
-
Parallel axis theorem: I = I_cm + Md²
-
Perpendicular axis theorem: I_z = I_x + I_y
Rotational Dynamics
-
Newton’s 2nd law (rotational form): τ = Iα
-
Work done by torque: W = τθ
-
Power: P = τω
Angular Momentum
-
Angular momentum: L = Iω = r × p
-
Conservation law: If no external torque acts, L = constant
Kinetic Energy in Rotation
-
Rotational KE: K = ½Iω²
-
Total KE of rolling body: K_total = ½mv² + ½Iω²
Moment of Inertia of Standard Bodies
-
Thin rod (axis through center, ⟂ length): I = (1/12)ML²
-
Thin rod (axis through end, ⟂ length): I = (1/3)ML²
-
Ring (axis through center, ⟂ plane): I = MR²
-
Disc (axis through center, ⟂ plane): I = (1/2)MR²
-
Sphere solid: I = (2/5)MR²
-
Sphere hollow: I = (2/3)MR²
Rolling Motion (Very Important for NEET)
-
Condition for rolling without slipping: v = Rω
-
Acceleration of rolling body on inclined plane:
a = (g sinθ) / (1 + (I / MR²))
NEET 2026 Tips for Rotational Motion
-
Always remember analogies between linear and rotational motion.
-
Focus on standard moment of inertia values – direct questions are common.
-
Practice rolling motion problems – they are frequently asked.
-
Don’t skip laws of conservation (energy & angular momentum).
NEET 2026 – Rotational Motion Objective Questions
Q1. The SI unit of torque is:
a) Joule
b) Newton-meter
c) Watt
d) Newton-second
Answer: The correct answer is (b) Newton-meter, because torque is the product of force and perpendicular distance.
Q2. Angular momentum of a particle is given by:
a) L = mv
b) L = Iα
c) L = r × p
d) L = F × t
Answer: The correct answer is (c) L = r × p, where p is the linear momentum.
Q3. For a rigid body rotating with angular velocity ω, rotational kinetic energy is:
a) ½mv²
b) ½Iω²
c) Iω
d) mgh
Answer: The correct answer is (b) ½Iω², which is the rotational analogue of kinetic energy.
Q4. The moment of inertia of a thin rod about an axis through its center, perpendicular to its length is:
a) (1/2)ML²
b) (1/3)ML²
c) (1/12)ML²
d) MR²
Answer: The correct answer is (c) (1/12)ML².
Q5. Torque is zero when:
a) Force is maximum
b) Angle between r and F is 0° or 180°
c) Force is perpendicular to r
d) Force is tangential
Answer: The correct answer is (b) Angle between r and F is 0° or 180°, because sinθ = 0.
Q6. Work done by torque in angular displacement θ is:
a) τ/θ
b) τθ
c) τ²θ
d) Iω²
Answer: The correct answer is (b) τθ, just like work = force × displacement in linear motion.
Q7. A rolling body without slipping satisfies:
a) v = ω/R
b) v = R/ω
c) v = Rω
d) v = ω²R
Answer: The correct answer is (c) v = Rω.
Q8. The perpendicular axis theorem is valid only for:
a) 3D bodies
b) Point masses
c) Plane laminae
d) Rigid spheres
Answer: The correct answer is (c) Plane laminae.
Q9. Angular acceleration is defined as:
a) dθ/dt
b) dω/dt
c) dv/dt
d) dr/dt
Answer: The correct answer is (b) dω/dt, the rate of change of angular velocity.
Q10. Power in rotational motion is given by:
a) P = Fv
b) P = τω
c) P = Iα²
d) P = Iω
Answer: The correct answer is (b) P = τω.
Q11. The moment of inertia of a solid sphere about its diameter is:
a) (2/5)MR²
b) (2/3)MR²
c) MR²
d) (1/2)MR²
Answer: The correct answer is (a) (2/5)MR².
Q12. The dimension of torque is the same as:
a) Energy
b) Force
c) Momentum
d) Power
Answer: The correct answer is (a) Energy, but torque and energy are not the same physical quantity.
Q13. If no external torque acts on a system, then:
a) Angular momentum is constant
b) Linear momentum is constant
c) Energy is always zero
d) Moment of inertia is constant
Answer: The correct answer is (a) Angular momentum is constant, by the law of conservation.
Q14. A disc and a ring of same mass and radius are released on an inclined plane. Who will reach first?
a) Ring
b) Disc
c) Both together
d) Depends on angle
Answer: The correct answer is (b) Disc, because it has smaller I/MR², so greater acceleration.
Q15. Rotational kinetic energy of a rolling sphere is:
a) ½Iω²
b) ½mv²
c) ½mv² + ½Iω²
d) Zero
Answer: The correct answer is (c) ½mv² + ½Iω², since it has both translational and rotational motion.
Q16. Which of the following is not a unit of angular velocity?
a) rad/s
b) degree/s
c) revolution/s
d) m/s
Answer: The correct answer is (d) m/s, which is a unit of linear velocity.
Q17. The parallel axis theorem is given by:
a) I = I_cm – Md²
b) I = I_cm + Md²
c) I = I_cm / Md²
d) I = MR²
Answer: The correct answer is (b) I = I_cm + Md².
Q18. The rotational analogue of force is:
a) Energy
b) Torque
c) Momentum
d) Angular velocity
Answer: The correct answer is (b) Torque.
Q19. For a particle moving in a circle with constant speed, angular velocity is:
a) Constant
b) Zero
c) Increasing
d) Decreasing
Answer: The correct answer is (a) Constant, since angular displacement per unit time is fixed.
Q20. Which physical quantity remains conserved when no external torque acts?
a) Angular momentum
b) Kinetic energy
c) Angular acceleration
d) Force
Answer: The correct answer is (a) Angular momentum.
Conclusion
Rotational Motion is a scoring chapter if your basics are clear. By memorizing the key formulas, standard values of moment of inertia, and understanding rolling motion, you can easily tackle NEET-level questions. Regular practice of MCQs will further boost your confidence.