Posts Tagged ‘tablecloth’

More Backyard Science- Tablecloth Trick

July 30, 2009

This is a fun experiment to try outside, on the grass, where your kids can spill as much water as they want to.   All you need is a table, a sturdy glass that won’t break if it falls on the grass, a slippery tablecloth and water.


We used easel paper as our tablecloth, but your kids could try a plastic tablecloth or even a cloth one that doesn’t have a heavy seam on the edge.  The more slippery the tablecloth, the better it will work. You’ll also need a fairy heavy glass that is not too tippy.  I used a bar glass and it worked pretty well.  I’d also recommend bringing out a pitcher of water for refilling the glass and a towel.

Have your child put the paper or tablecloth near the edge of the table (see photo above.)  Place the glass of water on the tablecloth.  I wouldn’t recommend filling it to the top.


This part is important!  Your child must pull the tablecloth straight down, along the edge of the table, very fast.  If they pull it out, toward them, or pull it too slowly, it won’t work.  If they do it correctly (and it may take a few attempts), the water will slosh a little, but the cup will remain on the table, full of water.  We spilled a lot, but had a great time.  All of the older kids involved were able to do it successfully by themselves, but I had to help my three year old a little.

The law of inertia says that objects don’t want to change how fast they’re moving (or not moving, in the case of our glass.)  They heavier something is, the more inertia it has.  In our experiment, the heavy glass of water is standing still and doesn’t want to speed up.  Since the tablecloth is moving under the glass very quickly, the heavy glass slips on it and doesn’t move very far.   It seems like magic, but it’s just physics.

Have fun!