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AIIMS 2012
Exam
AIIMS
Year
2012
Subject
Physics
Chapter
Rotational Motion

AIIMS 2012 · Physics · Rotational Motion

If 2 ~kg mass is rotating on a circular path of radius 0.8 ~m with...

If 2 kg2 \mathrm{~kg} mass is rotating on a circular path of radius 0.8 m0.8 \mathrm{~m} with angular velocity of 44rad/sec44 \mathrm{rad} / \mathrm{sec}. If radius of the path becomes 1 m1 \mathrm{~m}, then what will be the value of angular velocity?

Options

  1. A28.16rad/sec28.16 \mathrm{rad} / \mathrm{sec}
  2. B19.28rad/sec19.28 \mathrm{rad} / \mathrm{sec}
  3. C8.12rad/sec8.12 \mathrm{rad} / \mathrm{sec}
  4. D35.26rad/sec35.26 \mathrm{rad} / \mathrm{sec}

Correct answer

A. 28.16rad/sec28.16 \mathrm{rad} / \mathrm{sec}

Step-by-step solution

Mass (m)=2 kg(m)=2 \mathrm{~kg}; initial radius of the path (r1)=0.8 m\left(r_1\right)=0.8 \mathrm{~m}; initial angular velocity (ω1)=44rad/sec\left(\omega_1\right)=44 \mathrm{rad} / \mathrm{sec} and final radius of the path \left(r_2\right)=1 \mathrm{~m}Momentofinertia,Moment of inertia,I_1=m r_1^2=2 \times(0.8)^2 =1.28 \mathrm{~kg} \mathrm{~m}^2 and I_2=m r_2^2=2 \times(1)^2=2 \mathrm{~kg} \mathrm{\textrm {m } ^ { 2 }}ThereforefromthelawofconservationofangularmomentumTherefore from the law of conservation of angular momentumI_1 \omega_1=I_2 \omega_2 or \omega_2=\frac{I_1 \times \omega_1}{I_2}=\frac{1.28 \times 44}{2} \omega_2=28.16 \mathrm{rad} / \mathrm{sec}
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