Learn

Saturday, 31 October

JEE Main 2020 · PhysicsNumerical answerNumerical valueHardMulti-step

JEE Main 4 September 2020, Shift 1, Physics Q21

Question 21 of 75 in this shift, Physics question 21 of 25.

ABC is a plane lamina of the shape of an equilateral triangle. D, E are mid points of AB, AC and G is the centroid of the lamina. Moment of inertia of the lamina about an axis passing through G and perpendicular to the plane ABC is I0I_0. If part ADE is removed, the moment of inertia of the remaining part about the same axis is NI016\frac{NI_0}{16} where N is an integer. Value of N is __________.

The figure, in words

Triangle ABC with A at the top and B, C at the bottom left and right; D on side AB and E on side AC joined by a horizontal line DE; a dot labelled G lies inside the triangle below DE.

Official answer

11.00

NTA final key (Sep 2020).

Chapter
System of Particles and Rotational Motion
Topic
Moment of Inertia
Idea tested
MOI of a Triangular Plate

Same topic in other shifts

All Moment of Inertia questions
  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. 4 Apr 2026, Shift 1 · Q30A solid sphere of mass MM and radius RR is divided into two unequal parts. The smaller part having mass M/8M/8 is converted into a sphere…MediumSingle correct
  3. 6 Apr 2026, Shift 1 · Q31A solid sphere of radius 4 cm and mass 5 kg is rotating (rotation axis is passing through the centre of the sphere) with an angular…MediumSingle correct
  4. 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
  5. 2 Apr 2025, Shift 2 · Q28The moment of inertia of a circular ring of mass MM and diameter rr about a tangential axis lying in the plane of the ring is :EasySingle correct
  6. 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

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.