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NEET-XII-Physics

P1 year:2019

with Solutions - page 2
Qstn# 21 Prvs-QstnNext-Qstn
  • #21
    A solid cylinder of mass 2 kg and radius 4 cm
    rotating about its axis at the rate of 3 rpm.
    The torque required to stop after 2
    revolutions is
    (1) ``2 × 10^{{-6}}`` N m
    (2) ``2 × 10^{-3}`` N m
    (3) ``12 × 10^{-4}`` N m
    (4) ``2 × 10^6`` N m
    digAnsr:   1
    Ans : ( 1 )
    Sol. Work energy theorem.
    2 2
    f i
    1
    W I( )
    2
    = ω ω  = 2 revolution
    = 2 × 2 = 42 rad
    i
    2
    W 3 rad / s
    60
    = 
    2 2 2
    i
    1 1
    - mr (0 )
    2 2
    &implies;  =  ω
            
     &implies;  =

    2
    2
    2
    1 1 2
    2 (4 10 ) 3
    2 2 60
    -
    4
    6
    2 10 Nm

    &implies;  = 