JEE Main 2020 — Gravitation Question with Solution
From: JEE Main 2020 (Online) 2nd September Evening Slot
Question
The height ‘h’ at which the weight of a body will
be the same as that at the same depth ‘h’ from
the surface of the earth is (Radius of the earth
is R and effect of the rotation of the earth is
neglected)
Choose an option
Show full solutionCorrect option: B
Correct answer
B
Step-by-step explanation
M = mass of earth
M1 = mass of shaded portion
Re = Radius of earth
M1 =
=
Given, Weight of body is same at P and Q
mgP = mgQ
gP = gQ
(R – h) (R + h)2 = R3
R3 – hR2 + h2R – h3 + 2R2h – 2Rh2 = R3
R2h – Rh2 – h3 = 0
R2 – Rh – h2 = 0
h2 + Rh – R2 = 0
h =
h =
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This is a previous-year question from JEE Main 2020, covering the Gravitation chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.