Apparatus for investigating frictionless rotation. A small rotating disc with a protractor scale supports a cross bar to which weights can be attached. The disc is supported by a bed of air in which its axis is centered. A driving weight is suspended from a hook at the end of a string that is passed over a single pulley on one side and a multiple pulley on the other. The rotation is very slow and can be measured using a stopwatch by hand. Alternatively, a digital timer may be used. This can be started by a mechanism that is supplied with the kit and halted by a signal from a laser reflection sensor when the wheel passes through angle zero.

Experiment topics:

• Rotational motion: uniform and under constant acceleration
• Newton's equations of motion for rotational motion
• Moment of inertia and torque
• Moment of inertia as determined by experiment
• Simple harmonic motion of rotating objects

• Protractor scale: 0 - 360°
• Scale divisions: 1°
• Length of cross bar: ca. 440 mm
• Radii of perforations: 30 - 210 mm
• Separation of perforations: 20 mm
• Radii of multiple pulley: 5.0 mm/10.0 mm/15.0 mm
• Moment of inertia of
• disc with cross bar: 0.16 g m2 approx.
• Maximum moment of inertia: 7.1 g m2 approx.
• Minimum driving torque: 0.05 mN m approx.
• Maximum driving torque: 0.60 mN m approx.

• 1 Air bed
• 1 Rotating disc with cross bar
• 1 Multiple pulley
• 1 Release mechanism
• 2 S-shaped hooks 1.00g
• 1 S-shaped hook 2.00 g
• 1 Set of weights (2x 12.5 g, 2x 25 g, 2x 50 g)
• 1 Compressor for connection to mains
• 1 Silicon tubing with by-pass valve (not illustrated)
• 1 Pulley
• 1 Stand rod with 3 securing screws and 2 screws for leveling
• 1 Stand rod with 2 securing screws
• 1 Stand rod, 250 mm
• 1 Leveling disc
• 1 Roll of cotton thread