JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 5 September 2020, Shift 1, Physics Q7

Question 7 of 75 in this shift, Physics question 7 of 25.

A hollow spherical shell at outer radius R floats just submerged under the water surface. The inner radius of the shell is r. If the specific gravity of the shell material is

\frac{27}{8}

w.r.t water, the value of r is :

(1) $\frac{2}{3}R$
(2) $\frac{4}{9}R$
(3) $\frac{1}{3}R$
(4) $\frac{8}{9}R$ Official answer

Official answer

Option 4

NTA final key (Sep 2020).

Chapter: Mechanical Properties of Fluids
Topic: Fluid Statics
Idea tested: Law of Floatation

Same idea in other shifts

Asked 4× in all

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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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.