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NTA Abhyas JEE Main2020PhysicsRotational MotionPractice

An automobile moves on a road with a speed of 54 k m h - 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 k g m 2 . If the vehicle is brought to rest in 15 s , the magnitude of average torque transmitted by its brakes to the wheel is:

Options

  1. A8.58 k g m 2 s - 2
  2. B10.86 k g m 2 s - 2
  3. C2.86 k g m 2 s - 2
  4. D6.66 k g m 2 s - 2

Correct answer

D. 6.66 k g m 2 s - 2

Step-by-step solution

ω i = 15 0.45 = 100 3 ω f = 0 ω f = ω i + α t 0 = 100 3 + - α ( 15 ) α = 100 45 τ = I α = 3 × 100 45 = 6.66 N . M

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