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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedEasyCalculation

JEE Main 4 September 2020, Shift 2, Physics Q5

Question 5 of 75 in this shift, Physics question 5 of 25.

For a uniform rectangular sheet shown in the figure, the ratio of moments of inertia about the axes perpendicular to the sheet and passing through O (the centre of mass) and O′' (corner point) is :

The figure, in words

A rectangle with a y axis (labelled y, at the left, extending slightly above the top edge) and an x axis (labelled x, with an arrowhead, along the bottom edge extending to the right). The width is marked 60 cm (double-headed arrow below the bottom edge) and the height is marked 80 cm (double-headed vertical arrow to the right of the right edge). A point O (dot, labelled O) is drawn inside the rectangle near its centre. O' is labelled at the top-right corner, above the corner.
  1. (1)2/3
  2. (2)1/2
  3. (3)1/4Official answer
  4. (4)1/8

Official answer

Option 3

NTA final key (Sep 2020).

Chapter
System of Particles and Rotational Motion
Topic
Moment of Inertia
Idea tested
Parallel Axis Theorem

Same idea in other shifts

Asked 7× in all
  1. 2 Apr 2026, Shift 2 · Q50Moment of inertia about an axis ABAB for a rod of mass 40 kg and length 3 m is same as that of a solid sphere of mass of 10 kg and radius…MediumNumerical valueHas a figure
  2. 31 Jan 2024, Shift 2 · Q52Two identical spheres each of mass 2 kg and radius 50 cm are fixed at the ends of a light rod so that the separation between the centers…MediumNumerical value
  3. 26 Aug 2021, Shift 2 · Q10The solid cylinder of length 80 cm and mass M has a radius of 20 cm. Calculate the density of the material used if the moment of inertia…MediumDiagram basedHas a figure
  4. 27 Aug 2021, Shift 1 · Q2Moment of inertia of a square plate of side ll about the axis passing through one of the corner and perpendicular to the plane of square…EasySingle correct
  5. 31 Aug 2021, Shift 2 · Q14A system consists of two identical spheres each of mass 1.5 kg and radius 50 cm at the ends of a light rod. The distance between the…MediumSingle correct
  6. 26 Feb 2021, Shift 1 · Q5Four identical solid spheres each of mass ‘m’ and radius ‘a’ are placed with their centres on the four corners of a square of side ‘b’.…MediumSingle correct

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.