2025
Q1. A solid sphere and a hollow sphere of same mass and radius roll down an incline without slipping. Which reaches the bottom first?
(a) Hollow sphere
(b) Solid sphere
(c) Both reach together
(d) Depends on height
Answer: (b)
Solution: Smaller moment of inertia → greater acceleration. Solid sphere (I = 2/5 MR²) < Hollow (2/3 MR²).
Q2. Torque acting on a body is zero. Which quantity must be conserved?
(a) Linear momentum
(b) Angular momentum
(c) Kinetic energy
(d) Force
Answer: (b)
🟢 2024
Q3. A disc of radius R rotates with angular speed ω. Linear speed of a point at R/2 is:
(a) ωR
(b) ωR/2
(c) 2ωR
(d) ω²R
Answer: (b)
v = rω
Q4. Radius of gyration of a thin rod about its centre is:
(a) L/12
(b) L/√12
(c) L/2
(d) √12 L
Answer: (b)
🟢 2023
Q5. A constant torque produces angular acceleration α. If moment of inertia is doubled, α becomes:
(a) same
(b) half
(c) double
(d) zero
Answer: (b)
τ = Iα
Q6. Work done in rotating a body through angle θ under constant torque τ is:
(a) τ/θ
(b) τθ
(c) θ/τ
(d) τ²θ
Answer: (b)
🟢 2022
Q7. Angular momentum of a particle moving in circle is:
(a) mrω
(b) mr²ω
(c) mω²r
(d) mr
Answer: (b)
Q8. A skater pulls arms inward. What happens?
(a) ω decreases
(b) ω increases
(c) I increases
(d) L decreases
Answer: (b)
Conservation of angular momentum.
🟢 2021
Q9. Kinetic energy of rolling body =
(a) only translational
(b) only rotational
(c) sum of translational & rotational
(d) zero
Answer: (c)
Q10. Moment of inertia depends on:
(a) mass only
(b) radius only
(c) axis of rotation
(d) speed
Answer: (c)
🟢 2020
Q11. If no external torque acts, angular momentum remains:
(a) zero
(b) constant
(c) increasing
(d) decreasing
Answer: (b)
Q12. Torque is maximum when angle between r and F is:
(a) 0°
(b) 30°
(c) 90°
(d) 180°
Answer: (c)
🟢 2019
Q13. A ring and disc have same mass & radius. Which has greater moment of inertia about centre?
(a) Disc
(b) Ring
(c) Same
(d) Depends on speed
Answer: (b)
Q14. Rotational KE =
(a) ½ mv²
(b) ½ Iω
(c) ½ Iω²
(d) Iω
Answer: (c)
🟢 2018
Q15. Parallel axis theorem:
I = ?
(a) Icm + Md²
(b) Icm – Md²
(c) Md²
(d) Icm/d²
Answer: (a)
Q16. Angular velocity unit is:
(a) rad/s
(b) m/s
(c) rad
(d) N
Answer: (a)
🟢 2017
Q17. Relation between linear and angular acceleration:
(a) a = rα
(b) a = α/r
(c) a = r/α
(d) a = r²α
Answer: (a)
Q18. If radius doubles, moment of inertia becomes:
(a) I
(b) 2I
(c) 4I
(d) I/2
Answer: (c)
🟢 2016
Q19. Centre of mass of uniform ring lies at:
(a) edge
(b) centre
(c) outside
(d) none
Answer: (b)
Q20. Dimensional formula of angular momentum:
(a) ML²T⁻¹
(b) MLT⁻¹
(c) ML²T⁻²
(d) MLT⁻²
Answer: (a)
🟢 2015
Q21. Rolling without slipping condition:
(a) v = r/ω
(b) v = rω
(c) v = ω/r
(d) none
Answer: (b)
Q22. A body in equilibrium must have:
(a) ΣF = 0 only
(b) Στ = 0 only
(c) Both ΣF = 0 and Στ = 0
(d) none
Answer: (c)
🟢 2014
Q23. Flywheel stores energy in form of:
(a) Potential
(b) Rotational KE
(c) Heat
(d) Magnetic
Answer: (b)
Q24. If torque is constant, angular momentum varies:
(a) linearly with time
(b) quadratically
(c) constant
(d) zero
Answer: (a)
🟢 2013
Q25. Unit of torque is:
(a) N/m
(b) Nm
(c) J/s
(d) kg m
Answer: (b)
Q26. For a solid cylinder, I about central axis is:
(a) MR²
(b) ½ MR²
(c) 2/5 MR²
(d) 2/3 MR²
Answer: (b)