Classical mechanicsLesson 1 of 2 in the course Fixed-Axis Rotation

Constant Angular Acceleration: Equations, Applications, and Graphs

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson introduces the rotational quantities used to describe motion about a fixed axis and explains how constant angular acceleration affects angular velocity.

Angular displacement is measured in radians. The angular velocity ω\omega describes how quickly angular position changes, while the angular acceleration α\alpha describes how quickly angular velocity changes. Their SI units are radians per second (rad/s\text{rad/s}) and radians per second squared (rad/s2\text{rad/s}^2), respectively.

All flashcards

Angular displacement
The change in angular position: Δθ=θf−θ0\Delta\theta=\theta_f-\theta_0.
Constant angular acceleration
Angular acceleration that does not change with time; angular velocity then changes linearly with time.
Angular velocity-time graph slope
The slope of an angular velocity-time graph gives angular acceleration.
Angular acceleration-time graph area
The signed area under an angular acceleration-time graph gives the change in angular velocity.
Radians and revolutions
One revolution corresponds to 2π2\pi radians.

Quiz questions

  1. A wheel has initial angular velocity 3 rad/s3\ \text{rad/s} and constant angular acceleration 2 rad/s22\ \text{rad/s}^2 for 4 s4\ \text{s}. What is its final angular velocity?Answer: 11 rad/s11\ \text{rad/s}
  2. Which equation relates final angular velocity, initial angular velocity, angular acceleration, and angular displacement without using time?Answer: ωf2=ω02+2αΔθ\omega_f^2=\omega_0^2+2\alpha\Delta\theta
  3. A reel rotates through 220 rad220\ \text{rad}. Approximately how many revolutions is this?Answer: About 35.035.0 revolutions
  4. What physical quantity is represented by the slope of an angular velocity-time graph?Answer: Angular acceleration
  5. What does the signed area under an angular velocity-time graph represent?Answer: Angular displacement

Based on University Physics Volume 1 by William Moebs, Samuel J. Ling, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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