Coins

I have an almighty collection of very clean 1 cent coins. No vending machine will take them, and I can rarely be bothered to look through my pockets at the checkout to find the exact change, and get a couple of coins more. If I empty the pockets carefully when I put the trousers in the wash, these coins end up on my floor. If not, they end up in the washing machine, then on my floor.

Yesterday I found a use for 1 cent coins: demonstrating the independence of horizontal and vertical motion. Some people are surprised by the following experiment, so I showed it to my student.


The three coins need to be in contact, and the two small coins must balanced on the edge of the table. Hold the top 2€ coin with one thumb, and flick the bottom 2€ coin towards it with the other hand. The top 1c should fly off much faster than the one on the left, but they should start to fall at the same time. See which coin hits the floor first. It helps here if the floor is hard enough for a coin to make a nice clink when it hits the floor.

If you do this in the pub (or anywhere where someone else does the cleaning up), you can dispose of 1c coins quickly and painlessly, and learn about the world at the same time.