Homemade chemistry-lab style battery in a beaker.

This is actually just show and tell, lead plate and lead/lead oxide plate in a battery jar.

Use a gel cell battery to show electrical current at an integer multiple of the cell voltage between lead and lead oxide in sulfuric acid. Two volts is not as useful as six volts, or twelve and more.

Ball drops from mast of PASCO cart; its motion can be considered relative to the moving cart or the track frame of reference.

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Evaporation of water on duck's head cools vapor inside causing low pressure, etc.

How it works:

Dippy Duck is a small heat engine consisting of a hollow glass barbell with opposite ends able to seesaw about a knife edge pivot. One end of the barbell is filled with a high vapor pressure liquid. The other end is empty on the inside and coated with absorbent flocking on the outside.

When the flocking is wet, evaporative cooling reduces the air pressure inside the empty end of the barbell, causing the liquid at the other end to get sucked up into it. As the liquid rises...