JEE Main 2020PhysicsGravitationHardMCQ

JEE Main 2020 — Gravitation Question with Solution

JEE Main 2020 (07 Jan Shift 1)

Question

A satellite of massM  is launched vertically upwards with an initial speed u from the surface of the earth. After it reaches height R ( R= radius of the earth), it ejects a rocket of mass M10 so that subsequently the satellite moves in a circular orbit. The kinetic energy of the rocket is ( G is the gravitational constant; Me is the mass of the earth):

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Show full solutionCorrect option: B
Correct answer
B5Mu2-119200GMeR

Step-by-step explanation

-GMeMR+12Mu2=-GMeM2R+12Mv2

 

v=u2-GMeR

Vτ→ Transverse velocity of rocket 
VR→ Radial velocity of rocket

V=GMe2R

M10VT=9M10GMe2R
M10Vr=Mu2-GMeR

Kinetic energy =12M10VT2+Vr2=M2081GMe2R+100u2-100GMeR

=M20100u2-119GMe2R
=5Mu2-119GMe200R

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About this question

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.