A flywheel is rotating with an angular velocity of 20 rad/s. If it comes to rest

Practice Questions

Q1
A flywheel is rotating with an angular velocity of 20 rad/s. If it comes to rest in 5 seconds, what is the angular deceleration?
  1. 4 rad/s²
  2. 5 rad/s²
  3. 20 rad/s²
  4. 0 rad/s²

Questions & Step-by-Step Solutions

A flywheel is rotating with an angular velocity of 20 rad/s. If it comes to rest in 5 seconds, what is the angular deceleration?
Correct Answer: 4 rad/s²
  • Step 1: Identify the initial angular velocity (ω_i). In this case, it is 20 rad/s.
  • Step 2: Identify the final angular velocity (ω_f). Since the flywheel comes to rest, ω_f is 0 rad/s.
  • Step 3: Identify the time (t) it takes to come to rest. Here, t is 5 seconds.
  • Step 4: Use the formula for angular deceleration (α): α = (ω_f - ω_i) / t.
  • Step 5: Substitute the values into the formula: α = (0 rad/s - 20 rad/s) / 5 s.
  • Step 6: Calculate the result: α = -20 rad/s / 5 s = -4 rad/s².
  • Step 7: The negative sign indicates deceleration. The magnitude of angular deceleration is 4 rad/s².
  • Angular Deceleration – Angular deceleration is the rate of decrease of angular velocity, calculated as the change in angular velocity over time.
  • Kinematics of Rotational Motion – Understanding the relationships between angular velocity, angular acceleration, and time in rotational motion.
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