Rotational Kinematics
Rotation obeys equations like linear motion.
About this topic
Rotational motion mirrors linear motion with angular quantities: θ replaces s, ω replaces v, and α replaces a. For constant angular acceleration: ω = ω₀ + αt, θ = ω₀t + ½αt², and ω² = ω₀² + 2αθ. This means any technique you learned for straight-line motion transfers directly to spinning objects.
Link to linear quantities by s = rθ, v = rω and a = rα for the tangential part of acceleration. A point on a spinning object also has centripetal acceleration a = ω²r toward the axis, which is separate from the tangential acceleration. All angles must be in radians for these links to work.
Worked example: a flywheel starts from rest and accelerates at 4 rad/s² for 5 s. Its final angular speed is ω = 0 + 4 × 5 = 20 rad/s, and it turns through θ = ½ × 4 × 25 = 50 rad, about 8 revolutions. If its radius is 0.5 m, the rim then moves at 10 m/s.
Applications include car engines and wheels, washing machine spin cycles, disc drives, turbines and amusement park rides. A common slip is mixing revolutions, degrees and radians in one equation; convert everything first. Another is applying the constant-acceleration equations when α is changing, which they don't allow.
Key ideas
- θ = ω₀t + ½αt²
- ω = ω₀ + αt
- α is angular acceleration
Quick check
Use cases: where Rotational Kinematics helps
- Homework: review the key idea behind Rotational Kinematics before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Rotational Kinematics without notes.
- Visual learning: play with the interactive lab to see how Rotational Kinematics changes when you adjust its inputs.
- Teaching a friend: explain Rotational Kinematics in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Rotational Kinematics?
Rotation obeys equations like linear motion.
What will I learn in Rotational Kinematics?
θ = ω₀t + ½αt². ω = ω₀ + αt. α is angular acceleration.
Is Rotational Kinematics part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Rotational Kinematics lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Rotational Kinematics?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.