JEE Main 2021PhysicsWork Power EnergyMediumMCQ

JEE Main 2021 — Work Power Energy Question with Solution

JEE Main 2021 (31 Aug Shift 2)

Question

A block moving horizontally on a smooth surface with a speed of 40 m s-1 splits into two parts with masses in the ratio of 1 : 2. If the smaller part moves at 60 m s-1 in the same direction, then the fractional change in kinetic energy is :

Choose an option

Show full solutionCorrect option: D
Correct answer
D18

Step-by-step explanation


m×40=23mv+m3×60
120=2v+60
v=30 m s-1
Now Ki=12×m×402=800m
Kf=12×2 m3(30)2+12×m3×(60)2
=16{ m(1800+3600)}=m(5400)6=900m
ΔKEKi=900m-800m800m=18

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About this question

This is a previous-year question from JEE Main 2021, covering the Work Power Energy 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.