Stretchy water
Water, what an amazing substance. Yes, I know I have said this before, but is so much fun (not to mention inexpensive and often messy) to investigate the properties of water.
Did you know water has the ability to stretch itself out and not break? How can that be… well, we better investigate further. Let’s get started!
Remember to ask an adult before doing this experiment.
Materials
— One clear glass
— Water
— Lots of pennies
— Sturdy work surface that can get wet
Procedure
1. Fill the glass full of water, make sure you get it as full as possible. To do this, set it on the flat surface, get down at eye level and look at the meniscus. If you look at eye level, you will see that the water is not in a straight line, it curves down slightly. When you are standing up, the container will look much more full than if you get down and pour your water in.
2. It is time to make a hypothesis. How many pennies do you think you can add to the glass of water without it spilling out over the edge of the glass and WHY? Is this even possible? The glass is full, how can you fit any more in?
3. Carefully drop one penny down the side of the glass into the water. Continue to add until the water begins to spill out.
4. How many pennies did it take? How close was your hypothesis?
What is going on?
The reason you were able to add all of those pennies to the already FULL glass of water is because of surface tension. Surface tension is a special force which causes the water to behave like an elastic band – all stretchy.
As you add the pennies to the cup, the surface tension holds the surface of the water together instead of breaking it apart and spilling out over the edges. It literally stretches out ABOVE the cup. Bend down and observe closely!
Do not forget that the deadline to register for the Regional Science Fair is fast approaching. Grades 7-12 are due by March 22 and Grades 4-6 is April 8. Never hesitate to reach out if you have any questions. I am hoping to “see” you all at the virtual fair!
Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, www.praxismh.ca, Tweet or follow us @ PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, AB, T1A 1T7 Phone: 403-527-5365, email: praxis@praxismh.ca.