Previous Year Questions
Decoded & Patterned
What gets asked, how often, and how to prepare for it — all in one place.
CBSE 10-Year Trends (2014–2024)
Weightage by Subtopic
Marks Distribution
CBSE consistently asks: (1) A 2-mark definition question (torque or angular momentum), (2) A 3-mark derivation (parallel axis theorem or angular momentum conservation), (3) A 5-mark numerical (rolling motion or MI calculation). This 3-question pattern has repeated in 8 of the last 10 years.
Frequently Asked CBSE Questions
This has appeared 4 times in last 10 years. Always asked as a 5-mark question. Steps: (1) Take thin disc element at distance x, (2) dI = ½(dm)r² where r = √(R²-x²), (3) Integrate from -R to +R. Final answer: I = 2MR²/5.
Write this derivation in your CBSE exam step by step. Examiners give step marks even if your integration has an error.
I = I_cm + Md². Proof: Let I_cm be known. New axis parallel at distance d. For mass element m_i: r_i_new² = (x_i+d)² + y_i² = x_i² + y_i² + 2dx_i + d². Sum: ΣI = I_cm + Md² + 2d Σm_ix_i. But Σm_ix_i = 0 (COM is origin). Hence I = I_cm + Md².
Setup: Write F = ma along incline, τ = Iα about COM, and rolling constraint a = Rα. Solve simultaneously. Result: a = g sinθ/(1 + I/mR²) = g sinθ/(1 + k²/R²).
Forgetting to write torque equation (τ = Iα) loses 2 marks. You must have all 3 equations to get full marks.
NEET 10-Year Trends (2014–2024)
Question Frequency by Topic
NEET Difficulty Spread
Year-wise NEET Questions
| Year | Q1 Topic | Q2 Topic | Difficulty |
|---|---|---|---|
| 2024 | Rolling motion (KE) | Angular momentum conservation | Moderate |
| 2023 | Moment of Inertia (disc) | Torque (conceptual) | Easy |
| 2022 | COM of system | Rolling on incline (velocity) | Moderate |
| 2021 | Angular momentum (planet) | MI theorems | Easy |
| 2020 | Torque calculation | Rolling KE fraction | Moderate |
| 2019 | COM (cavity method) | Conservation of L (skater) | Moderate |
| 2018 | Parallel axis theorem | Rolling acceleration | Easy |
| 2017 | Angular velocity (ω = 2πf) | COM (semicircular ring) | Easy |
| 2016 | Torque and equilibrium | Angular momentum (L = Iω) | Easy |
| 2015 | MI of system of particles | Rolling body on incline | Moderate |
NEET questions from this chapter are doable in 60–90 seconds each. Focus on: (1) All MI formulas (memorised), (2) Rolling motion KE formula, (3) Angular momentum conservation setup. If you can do these 3 types blindfolded, you'll definitely score from this chapter in NEET.
JEE Main 10-Year Trends (2015–2024)
Topic Frequency (per 10 years)
Marks at Stake
JEE Main: 2–3 questions per year from this chapter → 8–12 marks. With negative marking, getting all right gives net +12, getting all wrong gives −4.
JEE Main (2019 onwards) shifted to numerical value questions (no options). This means you must get exact answers. Common traps: (1) Using wrong MI formula, (2) Forgetting to square ω in KE = ½Iω², (3) Using degrees instead of radians. The "numerical type" questions in this chapter typically involve: rolling body, MI using theorems, or angular impulse.
Repeating JEE Main Question Patterns
Given I about one axis, find I about another using parallel/perpendicular axis theorems. Appears in 7 of 10 years. Usually 2 steps.
Bullet hits disc/rod, embeds, find final angular velocity. Tests angular momentum conservation + MI calculation.
"What fraction of KE is rotational for a rolling body?" Almost every year for NEET, sometimes JEE Main. Easy 4-marker.
Graph of L vs. t or τ vs. θ is given. Find angular velocity, work done, or torque. Tests graph reading + concept.
JEE Advanced 10-Year Trends (2014–2024)
Concept Frequency
JEE Advanced Difficulty Profile
JEE Advanced rotational problems are typically 3–5 step problems requiring simultaneous use of: torque equations, energy conservation, angular momentum conservation, and rolling constraints. In 2018 and 2021, JEE Advanced had pure rolling problems where the body goes through varying surfaces — requiring piecewise analysis. That is the level of depth expected.
JEE Advanced High-Difficulty Topics
A block on an incline: when does it topple vs. slide? Compare: τ_topple criterion and friction criterion. Whichever is reached first determines the outcome. Complex but patterned — once you see it once, you can handle any variant.
(1) Assume rolling/equilibrium. (2) Find required friction f = τ_net/R. (3) Find max static friction f_max = μN. (4) If f > f_max → body slips. (5) Separately check toppling: COM vertical must be within base. This two-condition check is the complete solution method.
Ball rolls inside/outside a curved bowl. Energy conservation gives speed at any point. Normal force condition gives where the ball leaves the surface. Combines rolling KE + circular motion + constraints.
Ball leaves surface when N = 0 → v² = gR cosθ. Combined with energy: find θ of leaving.
A spinning top precesses. The rate of precession = torque / angular momentum. This is the JEE Advanced concept that confuses most students — it requires vector understanding of angular momentum.
Torque changes the direction of L, not its magnitude. So L precesses around the vertical axis. The faster the spin (larger ω, larger L), the slower the precession (smaller Ω). This is the counterintuitive gyroscope behavior.