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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Rotational Mechanics

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Rotational Mechanics

A wheel rotating about its axis at a speed of 600 rpm (revolutions...

A wheel rotating about its axis at a speed of 600 rpm600 \text{ rpm} (revolutions per minute) is brought to rest by applying a constant torque for 1010 seconds. Determine the angular deceleration and the angular velocity 55 seconds after the torque is applied.

Options

  1. A1 rev/s21 \text{ rev/s}^2, 5 rev/s5 \text{ rev/s}
  2. B10 rev/s210 \text{ rev/s}^2, 50 rev/s50 \text{ rev/s}
  3. C60 rev/s260 \text{ rev/s}^2, 300 rev/s300 \text{ rev/s}
  4. D2π rev/s22\pi \text{ rev/s}^2, 10π rev/s10\pi \text{ rev/s}

Correct answer

A. 1 rev/s21 \text{ rev/s}^2, 5 rev/s5 \text{ rev/s}

Step-by-step solution

Initial angular velocity, ω0=600 rpm=60060 rev/s=10 rev/s\omega_0 = 600 \text{ rpm} = \dfrac{600}{60} \text{ rev/s} = 10 \text{ rev/s}

Final angular velocity, ω=0\omega = 0

Time taken to come to rest, t=10 st = 10 \text{ s}

Using the first equation of rotational motion, ω=ω0+αt\omega = \omega_0 + \alpha t

0=10+α(10)0 = 10 + \alpha(10)

α=−1 rev/s2\alpha = -1 \text{ rev/s}^2

The angular deceleration is 1 rev/s21 \text{ rev/s}^2.

Angular velocity after 5 s5 \text{ s} is ω′=ω0+αt′\omega' = \omega_0 + \alpha t'

ω′=10+(−1)(5)=5 rev/s\omega' = 10 + (-1)(5) = 5 \text{ rev/s}
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