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NEET 2015 (AIPMT) · Angular Momentum & its Conservation

Angular Momentum & its Conservation question from NEET 2015 (AIPMT)

Q71NEET 2015 · AIPMTEasy

Angular Momentum & its Conservation

An automobile moves on a road with a speed of 54 km h−1{}^{-1}. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is

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Answer: (c)

  1. v=54v = 54 km/h =15= 15 m/s, so ω0=vr=150.45=33.3\omega_0 = \dfrac{v}{r} = \dfrac{15}{0.45} = 33.3 rad/s.
  2. τ=Iω0t=3×33.315\tau = \dfrac{I\omega_0}{t} = \dfrac{3 \times 33.3}{15}
  3. τ=6.66\tau = 6.66 kg m2^2 s−2^{-2}, so the answer is (c).
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