Mechanics > Rotational Dynamics > Angular Momentum DCS# 1Q40.40
TRAIN ON A ROTATING TRACK
APPARATUS
train track mounted on a bicycle wheel
 on top of 202-11
model train engine
 202-15-A
key switch
 101-09-D4
6 V, 18 A transformer
 113-02-G1
foam padding
 202-01-A

DESCRIPTION
The track is mounted on the rim of a horizontal bicycle wheel.  With the system initially at rest, power up the train to show that the train and track rotate in opposite directions.  You can reverse the direction by pressing the switch two more times (each time power to the engine is interrupted, the state changes from forward to neutral to reverse, etc.).  When powered off, the wheel does not come to a complete stop but continues to drift a bit due to friction in the bearings.  Shorter trips minimize this problem.

Keep the voltage below 8 V so the train doesn't jump the track.
NOTES
The track should be leveled before use.

Clean the sliding electrical contacts and if necessary apply a thin layer of vaseline.

Engine may need oil occasionally (see instructions) and the track may need to be cleaned.

This demonstration can be used in the display case.