Saturday, February 13, 2010

The Great Coin Blowing Demonstration - Experiment #164

"Do you know anyone who can blow hard enough to blow a small coin all the way across the mouth of a glass? Of course you do. You can!

You will need: 
Drinking glass
Small coin

What to do: Put the drinking glass on a table. Balance the coin on the rim of the class like this: Blow sharply on the edge of the coin....Now, balance the coin on the rim of the glass again. This time you are going to blow the coin all the way across the open mouth of the glass so it lands on the table on the opposite side of the glass. Impossible? No, you can do it! Blow hard. The coin will probably fall into the glass the first few times you try. You must blow right at the edge of the coin....Don't place your lips too close to the coin. Stay back several inches and blow straight at the coin's edge. Blow hard and fast.


What happens: The first time you tried it, the coin fell off the rim of the glass. It may have fallen into the glass or onto the table. But that's what you expected, wasn't it? When you lined up everything correctly, the coin sailed across the glass and hit the opposite rim, but the force of the rapidly moving air kept it going.

Why: The coin is light enough for the moving air from your lungs to set it in motion. It had very little friction to overcome, because it was balanced delicately on the rim of the glass. It's all a matter of directing the coin in the path it needs to take. Air speed does the rest."

What happened when CKS tried it? When CKS tried it, she never got the coin across. She kept trying and trying and trying, but it never worked. The coin kept falling into the glass. Mad Dad Scientist was able to get the penny across the glass two times. But wait! For this to work, you have to line your mouth up with the edge of the coin.

CKS rating: 0 stars - Like cleaning my bedroom....thbbppppt!

No comments:

Post a Comment