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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueHardMulti-step

JEE Main 26 August 2021, Shift 1, Physics Q22

Question 22 of 90 in this shift, Physics question 22 of 30, Section B.

Consider a badminton racket with length scales as shown in the figure. If the mass of the linear and circular portions of the badminton racket are same (M) and the mass of the threads are negligible, the moment of inertia of the racket about an axis perpendicular to the handle and in the plane of the ring at, r2\frac{r}{2} distance from the end A of the handle will be __________ Mr2Mr^2.

The figure, in words

Badminton racket drawn horizontally: a straight handle from end A (left) to a circular ring with a gridded (threaded) interior at right, point P marked at the top of the ring. A vertical dotted axis line with a circular rotation arrow at its top lies at distance r/2 from end A (left edge); the handle length from this axis to the ring's left edge is marked 6r and the ring diameter is marked 2r.

Official answer

52

NTA final key.

Chapter
System of Particles and Rotational Motion
Topic
Moment of Inertia
Idea tested
MOI of Composite Bodies

Same idea in other shifts

Asked 6× in all
  1. 2 Apr 2025, Shift 1 · Q32Moment of inertia of a rod of mass 'M' and length 'L' about an axis passing through its center and normal to its length is 'α\alpha'. Now…MediumSingle correct
  2. 7 Apr 2025, Shift 1 · Q46A, B and C are disc, solid sphere and spherical shell respectively with same radii and masses. These masses are placed as shown in figure.…HardNumerical valueHas a figure
  3. 6 Apr 2023, Shift 1 · Q60Two identical solid spheres each of mass 2 kg and radii 10 cm are fixed at the ends of a light rod. The separation between the centres of…MediumNumerical value
  4. 28 Jul 2022, Shift 1 · Q60Four identical discs each of mass 'M' and diameter 'a' are arranged in a small plane as shown in figure. If the moment of inertia of the…MediumNumerical valueHas a figure
  5. 9 Jan 2020, Shift 1 · Q4Three solid spheres each of mass m and diameter d are stuck together such that the lines connecting the centres form an equilateral…MediumSingle correctHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.