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
centred. 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.
- 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 (2 × 12,5 g, 2 × 25 g, 2 × 50 g)
1 Compressor for connection to mains
1 Silicon tubing with by-pass valve (not illustrated)
1 Stand rod with 3 securing screws and 2 screws for levelling
1 Stand rod with 2 securing screws
1 Stand rod, 250 mm
1 Levelling disc
1 Roll of cotton thread