What is a full glass of water? Filled up to the rim? Try this science experiment to see who can make the fullest glass of water. My boys enjoyed challenging each other to try to make the water bulge just a little bit bigger…and bigger… and SPLASH! Try to see if the water bulge bursts with the same number of coins every time, or if some times it can handle more. What if you add the coins quickly vs slowly? Do the waves on top of the bulge matter?
What you need:
- glass
- water
- pennies
What you do:
- Fill the glass up to the rim.
- Let the surface of the water become smooth.
- Add coins to the glass of full water.
- Keep adding coins until a bulge of water forms on top of the glass.
For additional fun, you can always color the water. This may make the bulge even more visible, but can make clean up a bit messy.
Why it works:
Surface tension allows the water to bulge over the limit of the rim of the glass. Surface tension is the tendency of water molecues to want to stick together until forced apart. The water bulge will grow until it over hangs the rim so much that gravity forces the molecules apart. SPLASH!
