JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 26 February 2021, Shift 1, Physics Q8

Question 8 of 90 in this shift, Physics question 8 of 30, Section A.

Assume that a tunnel is dug along a chord of the earth, at a perpendicular distance (R/2) from the earth’s centre, where ‘R’ is the radius of the Earth. The wall of the tunnel is frictionless. If a particle is released in this tunnel, it will execute a simple harmonic motion with a time period :

(1) $\frac{2\pi R}{g}$
(2) $2\pi\sqrt{\frac{R}{g}}$ Official answer
(3) $\frac{1}{2\pi}\sqrt{\frac{g}{R}}$
(4) $\frac{g}{2\pi R}$

Official answer

Option 2

NTA final key.

Chapter: Gravitation
Topic: Orbital Mechanics
Idea tested: Oscillation in an Earth Tunnel

Same topic in other shifts

All Orbital Mechanics questions

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.