
m×40=32mv+3m×60
120=2v+60
v=30m s−1
Now Ki=21×m×402=800m
Kf=21×32m(30)2+21×3m×(60)2
=61m(1800+3600)=6m(5400)=900m
KiΔKE=800m900m−800m=81
JEE Main 2021 — Physics Mechanics
A block moving horizontally on a smooth surface with a speed of 40ms−1 splits into two parts with masses in the ratio of 1:2. If the smaller part moves at 60ms−1 in the same direction, then the fractional change in kinetic energy is :
Held on 31 Aug 2021 · Verified 6 Jul 2026.
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81
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