2C20.70 • Pythagoras Cup
Location: Cabinet 2
Photos show the demonstration used at the University of Texas at Austin.
Photos show the demonstration used at the University of Texas at Austin.
Concepts Conveyed:
- Siphon effect: As the siphon originally fills up with water, the pressure on the liquid is constant, and the cup can hold water. However, when the cup is filled too high and goes past the siphon, the pressure becomes uneven, and the water drains out of the cup due to gravity.
- The water will not drain if the cup is only half filled because it does not reach the siphon. When the cup is filled all the way up, there is a change of pressure within the siphon and the water drains out, with the top part of the water taking the bottom part of the water with it due to the chain effect and the weight of the water/gravity.
Instructions / Notes:
- Be sure to be holding the cup in the air and over the empty beaker to catch the water.
- Fill the cup up with water, but take care to not fill the cup up past the red line. The cup will hold the water as the pressure inside will be evenly distributed.
- Then, fill the cup past the line. The water will siphon out of the hole in the bottom, per the siphon effect.
- If desired, display cross section print to class so siphon is visible and to better understand how demo works.
Demo Staff Notes:
- Have the cup, cross-section of cup, a beaker for under the cup, and a beaker of colored water prepared and set on the table.
Last updated on March 24, 2025