Learn

Saturday, 31 October

JEE Main 2020 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 2 September 2020, Shift 2, Physics Q22

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

A square shaped hole of side l=a2l = \frac{a}{2} is carved out at a distance d=a2d = \frac{a}{2} from the centre ‘O’ of a uniform circular disk of radius a. If the distance of the centre of mass of the remaining portion from O is −aX-\frac{a}{X}, value of X (to the nearest integer) is __________.

The figure, in words

Shaded circular disk with centre O (dot). A dashed vertical line passes upward through O and a dashed horizontal line extends to the right from O beyond the disk. An arrow from O to the upper left is labelled a. A small square (unshaded) lies to the right of O with a dot at its centre; the distance from O to the square’s centre is marked d with a brace, and the square’s side is marked l = a/2 with a brace below it.

Official answer

23.00

NTA final key (Sep 2020).

Chapter
System of Particles and Rotational Motion
Topic
Center of Mass
Idea tested
COM of Cavity Bodies

Same idea in other shifts

Asked 3× in all
  1. 4 Aug 2021, Shift 1 · Q13Choose the correct option for the centre of mass of a uniform disc of radius ‘R’ from which a circular section of radius r (2r < R) has…MediumSingle correct
  2. 8 Jan 2020, Shift 2 · Q4As shown in fig. when a spherical cavity (centred at O) of radius 1 is cut out of a uniform sphere of radius R (centred at C), the centre…HardDiagram basedHas 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.