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Rotational Dynamics for JEE: 40 solved questions

Real JEE paper questions on rotational dynamics, part of rotational motion. Each opens with the options, the correct answer and a step-by-step solution. Papers run from 2009 to 2026. No sign-in needed to read them.

What this topic asks

• Rotational energy and released bodies — 18 questions
• Torque and angular acceleration — 13 questions
• Pulleys, strings and hanging masses — 8 questions
• Equilibrium on a rotating surface — 1 question

All 40 questions with solutions

• A light rope is wound around a hollow cylinder of mass 5 kg and radius 70 cm. The rope is pulled with a force… JEE Main 13th April 2nd Shift 2023
• A solid disc of radius 20 cm and mass 10 kg rotates at 600 rpm about a normal axis through its centre. The re… JEE Main 25th July 2nd Shift 2021
• A circular disk of radius R and mass M rotates about its perpendicular central axis under an external torque… JEE Main 23rd Jan 2nd Shift 2025
• A cord of negligible mass is wound around the rim of a wheel (spokes of negligible mass), mass 10 kg, radius… JEE Main 2nd April 1st Shift 2025
• Two masses 400 g and 350 g are suspended from the ends of a light string over a heavy pulley of radius 2 cm.… JEE Main 24th Jan 1st Shift 2026
• A uniform disc of mass M=4 kg and radius R=10 cm is mounted on a fixed horizontal axle. A block of mass m=2 k… JEE Main 28th June 2nd Shift 2022
• A uniform rod of mass m and length l is suspended horizontally by two identical light strings at its ends. Th… JEE Main 21st Jan 1st Shift 2026
• Assertion: An electric fan continues to rotate for some time after the current is switched off. Reason: The f… JEE Main 10th April 2nd Shift 2023
• A stationary horizontal disc is free to rotate about its axis. When a torque is applied, its kinetic energy a… JEE Main 9th April 1st Shift 2019
• The moment of inertia of a body about a given axis is 1.5 kg m². Initially at rest, to produce a rotational k… JEE Main 9th April 2nd Shift 2019
• A bob of mass m is tied to a massless string wound on a flywheel (disc) of radius r and mass m. Released from… JEE Main 7th Jan 1st Shift 2020
• A wheel of moment of inertia I and radius R is free to rotate about its centre. A massless string over its ri… JEE Main 9th Jan 2nd Shift 2020
• A solid cylinder is suspended symmetrically through two massless strings wound on it (a yo-yo). The distance… JEE Main 27th July 2nd Shift 2022
• A rod of length 50 cm is pivoted at one end. It is raised so that it makes 30° with the horizontal and releas… JEE Main 9th Jan 2nd Shift 2019
• A rigid massless rod of length 3l has masses 5M₀ and 2M₀ at its ends. It is pivoted at a point P at distance… JEE Main 10th Jan 2nd Shift 2019
• A thin rod MN, free to rotate in the vertical plane about the fixed end N, is held horizontal. When the end M… JEE Main Online 2018
• A pulley of radius 1.5 m is rotated about its axis by a force F=(12t-3t²) N applied tangentially (with t in s… JEE Main 27th July 1st Shift 2022
• A 20 kg uniform circular disk of radius 0.2 m is pin-supported at its centre and initially at rest. A constan… JEE Main 16th March 1st Shift 2021
• Two circular discs, each of radius 10 cm and mass 600 g, are joined at their centres by a rod of length 30 cm… JEE Main 28th Jan 1st Shift 2026
• A rectangular solid box of length 0.3 m is held horizontally, with one of its sides on the edge of a platform… JEE Main 8th April 2nd Shift 2019
• A metal coin of mass 5 g and radius 1 cm is fixed to a thin stick AB of negligible mass, with the stick lying… JEE Main 10th April 2nd Shift 2019
• A slender uniform rod of mass M and length l is pivoted at one end so that it can rotate in a vertical plane.… JEE Main 2017
• A uniform disc of radius R and mass M is free to rotate only about its axis. A string is wrapped over its rim… JEE Main Online 2017
• A mass m is supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If… JEE Main 2014
• A mass m hangs with the help of a string wrapped around a pulley on a frictionless bearing. The pulley has ma… JEE Main 2011
• A thin uniform rod of length l and mass m is swinging freely about a horizontal axis passing through its end.… JEE Main 2009
• Two masses m and 2m are connected by a light string going over a pulley (a disc) of mass 30m with radius r=0.… JEE Main 22nd Jan 2nd Shift 2026
• A flywheel having mass 3 kg and radius 5 m is free to rotate about a horizontal axis. A string having negligi… JEE Main 28th Jan 2nd Shift 2026
• A wheel of radius 0.2 m rotates freely about its centre when a string that is wrapped over its rim is pulled… JEE Main 2nd April 2nd Shift 2025
• A thin solid disk of 1 kg is rotating about its diameter axis at the speed of 1800 rpm. By applying an extern… JEE Main 8th April 2nd Shift 2025
• A string is wrapped around the rim of a wheel of moment of inertia 0.40 kg m² and radius 10 cm. The wheel is… JEE Main 9th April 1st Shift 2024
• One end of a straight uniform 1 m long bar is pivoted on a horizontal table. It is released from rest when it… JEE Main 9th Jan 1st Shift 2020
• A thin uniform rod X of mass M and length L is pivoted at a point on the rod a height L/3 above its lower end… JEE Main 24th Jan 2nd Shift 2026
• A cord is wound round the circumference of a wheel of radius r. The axis of the wheel is horizontal and the m… JEE Main 26th Feb 2nd Shift 2021
• A uniform rod of length l is pivoted at one of its ends on a vertical shaft of negligible radius. When the sh… JEE Main 3rd Sept 2nd Shift 2020
• A thin uniform rod of length 2 m, cross-sectional area A and density d is rotated about an axis passing throu… JEE Main 30th Jan 1st Shift 2023
• A disc of mass 1 kg and radius R is free to rotate about a horizontal axis passing through its centre and per… JEE Main 26th July 1st Shift 2022
• A 2 kg steel rod of length 0.6 m is clamped on a table vertically at its lower end and is free to rotate in a… JEE Main 1st Sept 2nd Shift 2021
• A pulley is made using a thin rim and two rods of length equal to the diameter of the rim, the two rods lying… JEE Main 21st Jan 2nd Shift 2026
• A bead of mass m stays at the point P(a,b) on a wire bent in the shape of a parabola y=4Cx² and rotating with… JEE Main 2nd Sept 1st Shift 2020