ANNOYANCE

It happens every time the prof calls a group of students to the board to solve a physics problem. Someone holds the chalk wrong and sends chills up and down the spines of everyone in the class with that familiar classroom torture technique: "squeaky chalk."

Why does a piece of chalk produce that hideous squeal? According to the book, The Flying Circus of Physics (With Answers), squealing chalk results from the phenomenon of "stick and slip." Incorrectly held chalk actually sticks to the blackboard. But when the writer bends the chalk enough, it suddenly slips and vibrates, sporadically striking the chalkboard and producing that squeal we hear. As the vibrations decrease, the friction between the chalk and the board increases until the chalk sticks again and the torture begins once more. 

"Chalk Talk", Campus Life, December, 1979.

Pastor Don Baker relates a story of Rev. Tom Erickson: The public Library has a system called "Dial-A-Tale." Anytime a young child wants to hear a fairy tale, he can call the number and a voice comes on reading a short fairy tale to the listening young ear. However, the number is only one digit different from Rev. Tom Erickson. Because the small fingers often make a mistake, Tom gets frequent calls from a child listening for a fairy tale. After several unsuccessful attempts to explain a wrong number to the small child, Tom felt he had only one alternative. He obtained a copy of Three Little Pigs, and set it by the phone. Now, whenever a child calls, he simply reads them the tale. A beautiful illustration of yielding personal rights. he didn't, as you might have thought, change his telephone number to avoid the "invasion of his privacy."

Don Baker.