JEE Main 2021PhysicsWork Power EnergyMediumNumerical

JEE Main 2021 — Work Power Energy Question with Solution

JEE Main 2021 (31 Aug Shift 1)

Question

A block moving horizontally on a smooth surface with a speed of 40 m s-1 splits into two equal parts. If one of the parts moves at 60 m s-1 in the same direction, then the fractional change in the kinetic energy will be x: 4 where x= ________.

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Correct answer
1

Step-by-step explanation

2m×40=60×m+mv
V=20 m/s
Now ΔKE=KEf-KEi=12 m×(20)2+12 m×(60)2-122 m×(40)2
ΔKE=12 m(800)⇒KEi=122 m×(40)2=12 m×3200
Fractional change =ΔKEKEi=14

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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.