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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctHardMulti-step

JEE Main 3 September 2020, Shift 2, Physics Q5

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

The mass density of a planet of radius R varies with the distance r from its centre as ρ(r)=ρ0(1−r2R2)\rho(r) = \rho_0\left(1 - \frac{r^2}{R^2}\right). Then the gravitational field is maximum at :
  1. (1)r=Rr = R
  2. (2)r=59 Rr = \sqrt{\frac{5}{9}}\,ROfficial answer
  3. (3)r=34 Rr = \sqrt{\frac{3}{4}}\,R
  4. (4)r=13 Rr = \frac{1}{\sqrt{3}}\,R

Official answer

Option 2

NTA final key (Sep 2020).

Chapter
Gravitation
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.