Physics & Physical Science Demos, Labs, & Projects for High School Teachers

I hope everyone that teaches inertia does this demonstration. I let the kids do it also. I have a couple dos and don’ts for making this a success.

• Pull the tablecloth out with a quick, single motion.  If you pull slowly, friction will start the dishes moving towards you.
• Choke up on the tablecloth. You want to have your full arms length to pull it. If the cloth is slack, you might only pull the tablecloth half way out.
• Friction is your enemy. A smooth, silky tablecloth works better than a rough, burlap bag.
• Pull quickly and pull slightly down. If you pull upward, you are likely to launch the dishes into the air.
• Make sure the tablecloth doesn’t have a hem. The edge of the plate and cup will snag on these and go flying.
• I tried this the first time with a dollar store tablecloth. The plate didn’t move, but the cloth ripped in half. Just a heads up.
• I’ve never had a failure at this demonstration.  The closest I’ve come is when one of the kids does the trick and starts to pull up.  I usually stand close by when it’s their turn.

I always tell the kids to make sure you go home and try this with mom’s good china. 😉