JEE Main 2021PhysicsGravitationHardMCQ

JEE Main 2021 — Gravitation Question with Solution

JEE Main 2021 (22 Jul Shift 1)

Question

A body is projected vertically upwards from the surface of earth with a velocity sufficient enough to carry it to infinity. The time taken by it to reach height h is           S.

Choose an option

Show full solutionCorrect option: D
Correct answer
D132Rcg1+hRe32-1

Step-by-step explanation

Applying energy conservation from (1 to 2,
12 m·2GMRe-GMmRe=12 mv2-GMmR+r

⇒12mv2=GMmR+r

⇒v=2GMR+r=drdt

⇒ 2GM∫0tdt=∫ReRe+h(R+r)dr

2GM·t=23(R+r)32ReRe+h

t=23Re32GM1+hRe32-1

GMRe2=g

t=132Re g1+hRe32-1

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About this question

This is a previous-year question from JEE Main 2021, 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.