- Amal Augustine
- December 24, 2025
Rotational Inertia MCQs: Your Ultimate Practice Tool for Physics Mastery
Rotational Inertia MCQs play a crucial role in testing a student’s understanding of how mass distribution affects rotational behavior. These rational inertia mcqs questions connect moment of inertia, angular velocity, torque, radius of gyration, and energy relationships into numerical and conceptual problems. Mastering Rotational Inertia MCQs helps students confidently solve NEET, JEE, and board-level physics questions by applying formulas correctly and interpreting physical situations logically.
Rotational inertia mcqs(moment of inertia) mainly test how mass distribution affects a body’s resistance to angular acceleration. These rotational inertia mcqs questions emphasize that for the same mass, objects with mass farther from the axis of rotation always have a larger moment of inertia. Many rotational inertia MCQs compare rings, discs, rods, and composite bodies to check understanding of standard formulas and the parallel-axis and perpendicular-axis theorems.The following set of rotational inertia mcqs focuses purely on high-yield numericals and concepts for competitive exams.
Rotational Inertia MCQs -With Options & Answers
1.
From a circular ring of mass M and radius R, an arc corresponding to a 90° sector is removed. The moment of inertia of the remaining part about an axis through the centre and perpendicular to the plane is KMR².
A. 3/4
B. 7/8
C. 1/4
D. 1/8
Answer: A
2.
Which wheel of same mass and radius has the largest moment of inertia?
A. Ring
B. Angular disc
C. Solid disc
D. Cylindrical disc
Answer: A
3.
Moment of inertia of a thin rod (mass M, length L) about an axis at distance L/4 from centre and perpendicular to length is:
A. ML³/48
B. ML²/48
C. ML²/12
D. 7ML²/48
Answer: D
4.
Moment of inertia of a circular ring of radius 15 cm and mass 150 g is:
A. 0.008 kg·m²
B. 0.006 kg·m²
C. 0.004 kg·m²
D. 0.003 kg·m²
Answer: D
5.
Moment of inertia of a circular loop of radius R about the shown axis is:
A. MR²
B. 3/4 MR²
C. MR²/2
D. 2MR²
Answer: B
6.
A body of mass 1.5 kg rotates with angular velocity 0.3 rad/s and angular momentum 1.8 kg·m²/s. Radius of gyration is:
A. 0.2 m
B. 0.8 m
C. 1.2 m
D. 1.6 m
Answer: A
7.
A flywheel (I = 3×10⁻³ kg·m²) rotates at 4.6 rad/s. If a retarding torque is applied, the stopping time is:
A. 1.5 s
B. 0.5 s
C. 2 s
D. 2.5 s
Answer: B
8.
Moment of inertia of a ring about a tangent perpendicular to its plane is:
A. 5/2 MR²
B. 3/2 MR²
C. 1/2 MR²
D. MR²
Answer: B
9.
A body rotates with I = 1 kg·m² at 2 rev/s. Angular momentum is:
A. 1.257
B. 12.57
C. 13.57
D. 20
Answer: B
10.
If angular velocity is unity, moment of inertia equals:
A. Kinetic energy
B. Twice kinetic energy
C. Angular momentum
D. Twice angular momentum
Answer: B
11.
A point particle of mass 1 g moves in a circle of diameter 8 cm. Its moment of inertia is:
A. 2 g·cm²
B. 4 g·cm²
C. 8 g·cm²
D. 16 g·cm²
Answer: D
12.
Moment of inertia of a uniform ring about a tangent perpendicular to plane is:
A. 2MR²
B. 3/2MR²
C. 1/2MR²
D. MR²
Answer: A
13.
If external torque is zero, which quantity must be zero?
A. J
B. F
C. ω
D. α
Answer: D
14.
If Earth’s radius suddenly decreases, what happens?
A. Angular momentum increases
B. Time period increases
C. Energy and momentum constant
D. Angular velocity increases
Answer: D
15.
Ratio of moments of inertia of two discs (same material) with radii R and 4R is:
A. 32
B. 16
C. 1
D. 64
Answer: D
16.
Moment of inertia of a ring about its diameter is:
A. I
B. I/2
C. I/√2
D. I + MR²
Answer: B
17.
Radius of gyration of wheel (I = 160 kg·m², m = 10 kg):
A. 10 m
B. 4 m
C. 5 m
D. 6 m
Answer: B
18.
Incorrect relation is:
A. τ = Iα
B. τ = dipole × B
C. I = τ × α
D. L = Iω
Answer: C
19.
Four particles of mass m at corners of square side l. Radius of gyration is:
A. √2l
B. l/2
C. l
D. l/√2
Answer: D
20.
A circular disc is made of iron and aluminium to obtain maximum moment of inertia about its geometrical axis. The correct arrangement is:
A. Iron inside, aluminium outside
B. Aluminium inside, iron outside
C. Alternate layers of iron and aluminium
D. Either (A) or (C)
Answer: B
21.
A circular disc is prepared using iron and aluminium to achieve greater moment of inertia. This is possible when:
A. Iron and aluminium are in alternate layers
B. Aluminium is at interior and iron surrounds it
C. Iron is at interior and aluminium surrounds it
D. Either (A) or (C)
Answer: B
22.
PQR is a right-angled triangular lamina of uniform thickness. If I₁, I₂ and I₃ are moments of inertia about PQ, QR and PR respectively, then:
A. I₃ < I₂ < I₁
B. I₁ = I₂ = I₃
C. I₂ > I₁ > I₃
D. I₃ > I₁ > I₂
Answer: C
23.
A wheel of mass 10 kg has a moment of inertia of 160 kg·m² about its own axis. The radius of gyration is:
A. 10 m
B. 4 m
C. 5 m
D. 6 m
Answer: B
24.
Which of the following relations is incorrect?
A. Torque = Moment of inertia × Angular acceleration
B. Torque = Dipole moment × Magnetic induction
C. Moment of inertia = Torque × Angular acceleration
D. Angular momentum = Moment of inertia × Angular velocity
Answer: C
25.
Four particles each of mass m are placed at the corners of a square of side l. The radius of gyration of the system about an axis perpendicular to the square and passing through its centre is:
A. √2 l
B. l/2
C. l
D. l/√2
Answer: D
Conclusion
Rotational Inertia MCQs strengthen a student’s ability to analyze how mass distribution influences rotational motion. By practicing these rotational inertia mcqs numericals, learners gain clarity on moment of inertia formulas, parallel and perpendicular axis theorems, and real-world rotational systems. A strong command of Rotational Inertia MCQs not only improves exam accuracy but also builds conceptual confidence in rotational mechanics, one of the most scoring areas in physics.
Numerical problems often connect moment of inertia with angular momentum, rotational kinetic energy, and torque relations such as τ = Iα. Overall, rotational inertia MCQs assess both conceptual clarity and the ability to choose the correct physical model before applying formulas.
Amal Augustine is the founder of ExQuizMe, a dynamic learning and quiz platform built to make education engaging, competitive, and fun. A passionate learner and an academic achiever, Amal completed his schooling at Government HSS Manjapra, graduating with 92.5% in Computer Science. He later earned his degree from St. Stephen’s College, University of Delhi, one of India’s most prestigious arts and science institutions.
Currently, Amal is pursuing his Master’s degree at National Sun Yat-sen University, Taiwan, where he continues to deepen his interest in research and technology. Throughout his school and college years, he won 50+ national-level interschool and collegiate quiz competitions, was
Beyond academics, Amal Augustine is an avid reader of science journals, a dedicated research student, and a technology enthusiast who loves programming and exploring the world of Computer Science. Through ExQuizMe, he aims to make learning accessible, enjoyable, and empowering for students across the globe.