Disc vs Ring Moment of Inertia

A disc and a ring of equal mass and diameter are released down an inclined plane to compare their rolling speeds. The demonstration shows how mass distribution affects moment of inertia and influences rotational acceleration.

1. Place a clean inclined plane at an angle greater than 10 degrees.
2. Mark a start and finish line if you want to measure the race distance.
3. Position the disc and the ring side by side at the starting line.
4. Release both objects simultaneously and allow them to roll freely.
5. Observe which object reaches the bottom first.

Rotational Inertia: The Race Between a Ring and a Disc - North Carolina School of Science and Mathematics:

Moment of Inertia Race - Disc vs Ring - SMUPhysics:

📄 Disc vs Ring - Moment of Inertia - Classroom Physics Demos: https://demos.smu.ca/demos/mechanics/119-moment-of-inertia-race

• Try using objects of different sizes but similar shapes to compare results.
• Use a stopwatch to time the roll of each object and compare quantitative results.
• Increase the incline angle to see how it affects the speed difference.

• Ensure the inclined plane is stable to prevent it from tipping over.
• Keep hands and other objects clear of the rolling path.
• Use caution with heavy discs or rings to avoid injury if they fall.

• Why does the disc reach the bottom faster than the ring? (Because the disc has a smaller moment of inertia, so it accelerates more easily.)
• How would the results change if the masses were different? (The relative speed difference is due to mass distribution, not total mass, so results would be similar.)
• What role does conservation of energy play in this demonstration? (Potential energy converts into both translational and rotational kinetic energy, and the distribution determines speed.)