Verified Solution • 2025–26 Session moderate

QNEET-2019-Ph-795: NEET 2019 Physics - Class 11 NEET-2019-Ph-795 Solution: A solid cylinder of mass 2 kg and radius 4 cm is rotating about …

A solid cylinder of mass 2 kg and radius 4 cm is rotating about its axis at the rate of 3 rpm. The torque required to stop after 2π2\pi revolutions is: 2×10−3 N m2 \times 10^{-3}\ \text{N m} 2×10−6 N m2 \times 10^{-6}\ \text{N m} 2×106 N m2 \times 10^6\ \text{N m} 12×10−4 N m12 \times 10^{-4}\ \text{N m}

Multiple Choice Options

  • A 2 _ 10 �3 N m
  • B 2 _ 10 �6 N m
  • C 2 _ 10 6 N m
  • D 12 _ 10 �4 N m

Step-by-Step Verified Solution

Acccording to work energy theorem, W = 1 2 ( _ f 2 _ _ i 2 ) Given that, _ = 2 � revolution/minute _ = 2 � _ 2 � = 4 � 2 rad _ i = 3 _ 2 � 60 rad/s _ f = 0 rad/s By putting the value of _ f and _ i , we get - _ _ = 1 2 _ 1 2 m r 2 ( 0 _ _ i 2 ) _ _ = _ 1 2 _ 1 2 _ 2 _ ( 4 _ 10 _ 2 ) _ ( _ 3 _ 2 � 60 ) 2 4 � 2 = 2 _ 10 -6 Nm

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