Watch the magic of science as you turn a cup filled with water upside down and the water stays in the cup!
Impossible you might say, well try this experiment and learn about how this is possible with some understanding of air pressure.
Materials
Strong plastic clear cup
sturdy card that extends 2-3cm past the edge of the cup on all sides
water and maybe a mop (just in case)!
Remember
Slippage may occur if water is on the ground. Do this experiment over a sink or outside
Fill the cup 3/4 full of water and place the card on top of the cup.
Place you hand on the card and hold it firmly while you turn the cup upside down with your other hand.
Keep the card held in position for 10-20 seconds (for the water inside the cup to settle).
Carefully remove the hand holding the card and see if it falls or remains in place.
Magic!
Check out the ‘Wacky Science’ video of this experiment and ‘What’s Going On’ series link. They are currently ‘In Production’, so check back soon…..
Did you expect the water to fall out of the cup when it was upside down? Most people do.
That is because they expect gravity to pull it down to earth and push the paper card off the cup as well. That would happen IF we had no air pressure and attractive forces between water molecules!
If you would like
– more details,
– pictures of the second half of the experiment
– information on how to investigate this further
– links to everyday examples
– management hints & teaching pointers (5P Teacher develpoment program)
 ….. then why not subscribe to one of the following
(1) Crazy science Club
(2) 5P Teacher Training course called ‘Looney Lab  Classroom Creations‘
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Or you can purchase the ‘Bright Sparkes Guide’ of this demonstration only ($2.50) which has:
- HD pictures of experiment steps
- Detailed explanation of science
- Mini-challenge section (another experiment)
- Making it a ‘Scientific Method’ experience
- Graphing opportunities
- REAL links and descriptions to everyday examples of concept.
Water molecules: Water is made of microscopic particles called water molecules. They are made up of two hydrogen atoms joined to one oxygen atom.
Surface tension: This is the force produced when water molecules are attracted to each other.
Pressure: A measure of force per unit of area. In this experiment, atmospheric pressure is pushing on the card to keep it from falling off.