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Saturday, 31 October

JEE Main 2022 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 28 June 2022, Shift 2, Physics Q59

Question 59 of 90 in this shift, Physics question 29 of 30, Section B.

A uniform disc with mass M=4 kg and radius R=10 cm is mounted on a fixed horizontal axle as shown in figure. A block with mass m=2 kg hangs from a massless cord that is wrapped around the rim of the disc. During the fall of the block, the cord does not slip and there is no friction at the axle. The tension in the cord is __________ N. (Take g=10 ms−2^{-2})

The figure, in words

A dotted (shaded) disc labelled M mounted at the end of a horizontal hatched support at the top left; a cord wrapped over the rim of the disc hangs vertically down on the right and carries a small square block labelled m.

Official answer

10

NTA final key.

Chapter
System of Particles and Rotational Motion
Topic
Torque and Equilibrium
Idea tested
Torque of Tension on Pulleys

Same idea in other shifts

Asked 3× in all
  1. 3 Aug 2021, Shift 1 · Q8A pulley of mass mm and moment of inertia II about its axis is suspended as shown in the diagram. The spring has spring constant ‘kk'…MediumDiagram basedHas a figure
  2. 9 Jan 2020, Shift 2 · Q3A uniformly thick wheel with moment of inertia II and radius RR is free to rotate about its centre of mass (see fig). A massless string…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.