1Q10.75 • Rotational Inertia of Disk and Ring
Location: Cabinet 1
Photo shows the demonstration used at the University of Texas at Austin.
Concept conveyed:
- Rotational inertia of a mass ring and a disk around their respective centers of mass
- Change in angular momentum when mass is added
Instructions:
- Place the disk onto the rod in the middle of the base, with the side of the disk with the indentation facing up.
- Make sure the rod is aligned and goes all the way through the disk, including the semicircle piece on top.
- Spin the disk to see the revolutions. Stop the disk or wait for it to slow to a stop.
- Place the mass ring into the indentation. Spin the disk again to see the difference between the system with and without the mass ring - should be slower with the ring on the disk.
Notes:
- A stopwatch can be added, if requested, to help show the difference in speed per rotation.
- Use a stable table, and make sure the base is level. Clamp down for best results.
- Can also use this to show/measure the rotational inertia around the diameter of the disk by placing the disk on its side into the rod in the middle of the base. This shows the center of mass around the diameter.
- Be gentle when spinning!
Demo Staff:
- MAKE SURE the track is NOT on the base when setting this demo up. If the track is on the base, the disk will not fit right, and it will fall off and damage the track and/or disk.
- When putting the demo away, make sure to use the bags in the box for each part to prevent scratches.
- Bags are labeled with what experiment uses each part, as well as what belongs inside
- This is a part of the Complete Rotational System from PASCO.
Last updated on July 31, 2026