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NEET 2018
Exam
NEET
Year
2018
Subject
Physics
Chapter
Rotational Motion

NEET 2018 · Physics · Rotational Motion

Three objects, A : (a solid sphere), B : (a thin circular disk) and...

Three objects, AA: (a solid sphere), BB: (a thin circular disk)andCand C: (a circular ring), each have the same mass MM and radius RR. They all spin with the same angular speed ω\omega about their own symmetric axes. The amounts of work (W)( W ) required to bring them to rest, would satisfy the relation

Options

  1. AWB>WA>WC{W}_{B} > {W}_{A} > {W}_{C}
  2. BWA>WB>WC{W}_{A} > {W}_{B} > {W}_{C}
  3. CWC>WB>WA{W}_{C} > {W}_{B} > {W}_{A}
  4. DWA>WC>WB{W}_{A} > {W}_{C} > {W}_{B}

Correct answer

C. WC>WB>WA{W}_{C} > {W}_{B} > {W}_{A}

Step-by-step solution

By work-energy theorem

W=lossinKE=12Iω2W = lossinKE = \dfrac{1}{2}I{\omega}^{2}

IA=25MR2=0.4MR2{I}_{A} = \dfrac{2}{5}M{R}^{2} = 0.4M{R}^{2}

IB=12MR2=0.5MR2{I}_{B} = \dfrac{1}{2}M{R}^{2} = 0.5M{R}^{2}

IC=MR2{I}_{C} = M{R}^{2}

∴WC>WB>WA{∴ W}_{C} > {W}_{B} > {W}_{A}
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