Rotational Motion Question 87

Question: An automobile moves on a road with a speed of 54kmh1 . The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3kgm2 . If the vehicle is brought to rest in 15s, the magnitude of average torque transmitted by its brakes to the wheel is

Options:

A) 6.66kgm2s2

B) 8.58kgm2s2

C) 10.86kgm2s2

D) 2.86kgm2s2

Show Answer

Answer:

Correct Answer: A

Solution:

  • As velocity of an automobile vehicle, v=54km/hr=54×518=15m/s

    Angular velocity of a vehicle, v=ω0r

    ω0=vR=150.45=1003rad/s

    So, angular acceleration of an automobile,

    α=Δωt=ωtω0t=0100315=10045rad/s2

    Thus, average torque transmitted by its brakes to wheel

    τ=Iα

    3×10045=6.66kgm2s2

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    When mica is introduced, capacitance will increase hence voltage across capacitor, get decrease.



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