tea-bag accelerometer
this was a nice touch. it's a dangly tea bag outside the window on my train this morning. it had been dipped in milky tea so left a trail behind as it swung backwards and forwards as the train accelerated.
so, what we ended up with was a time based wind splodge showing the trains' acceleration ! what a great idea.
sadly these photos don't do it justice, but i think you can see what i was getting at.
Years ago, when they used to maintain the track BEFORE it broke, the engineers train would have a bucket of whitewash hanging from the last wagon. When it crossed a bit of rough track the whitewash would splash onto the track, leaving an indication for the platelayers.
Perhaps this is a variation on the same theme.