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Saturday, 31 October

JEE Main 2020 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 3 September 2020, Shift 2, Physics Q22

Question 22 of 75 in this shift, Physics question 22 of 25.

An massless equilateral triangle EFG of side 'a' (As shown in figure) has three particles of mass m situated at its vertices. The moment of inertia of the system about the line EX perpendicular to EG in the plane of EFG is N20ma2\frac{N}{20}ma^2 where N is an integer. The value of N is ________.

The figure, in words

A triangle with vertices E (bottom left), G (bottom right) and F (top, apex), side EG labelled a. A vertical line rises from E up to a point labelled X (above E, left of the triangle). Dots drawn at E, F and G.

Official answer

25.00

NTA final key (Sep 2020).

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

Same idea in other shifts

Asked 5× in all
  1. 6 Apr 2024, Shift 2 · Q56Three balls of masses 2 kg, 4 kg and 6 kg respectively are arranged at centre of the edges of an equilateral triangle of side 2 m. The…MediumNumerical value
  2. 27 Jan 2024, Shift 1 · Q52Four particles each of mass 1 kg are placed at four corners of a square of side 2 m. Moment of inertia of system about an axis…EasyNumerical value
  3. 26 Jul 2022, Shift 1 · Q52A disc of mass 1 kg and radius R is free to rotate about a horizontal axis passing through its centre and perpendicular to the plane of…HardNumerical value
  4. 30 Jun 2022, Shift 1 · Q53Four particles with a mass of 1 kg, 2 kg, 3 kg and 4 kg are situated at the corners of a square with side 1 m (as shown in the figure).…EasyNumerical valueHas 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.