1Q10.80 • Moment of Inertia: Rotational Inertia of Disk Off-Axis

Location: Cabinet 1

Photo shows the demonstration used at the University of Texas at Austin.

Concept conveyed:

Instructions:

Place the track on the base, and attach the silver platform adapter to about at the 15 cm mark on the track from the edge of the track.
Put the disk with the ring indentation (or "Disk” label) face down. Spin the track. The rotations should not be stable/consistent throughout a single rotation. It should speed up and slow down in specific spots in its rotation.
Attach the two square 300 g masses on the opposite end of the platform, at about the 18 and 12 cm mark, to counterbalance the disk mass. Spin the track again to see smooth rotations with consistent velocity throughout each rotation.
Change the distance from the center of the track to change the speed of the rotations, making sure the masses and the disk are a proportional distance apart.

Notes:

Use a stable table, and make sure the base is level. Clamp down for best results.
Make sure to tighten all screws/bolts to keep everything in place.
To put anything onto the track, line the square nut up with the grooves in the track and slide in.
The track scratches very easily, so be careful when tightening each component into place on the track.
If the platform adapter gets stuck on the track, put the disk back on and turn the disk to help loosen the adapter.
Be gentle when spinning!

Demo Staff:

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