Mechanical Engineering News

An internet publication of the Mechanical Engineering Division of the American Society for Engineering Education

AMUSEMENTS

Take five times which plus half of what and make the square of what you've got. Divide by one and thirty square, to get just four - that's right, it's there. Now just two more points I must impress: both which and what are fractionless, and what less which is not a lot: Just two or three. So now, what's what? 

PUZZLES
I received some some puzzles a while ago, and I do not know where they originated. However, they make for interesting reading. If you know the source document, please so notify me so that I can appropriately acknowledge the original publication. Here's a few.

A cube of ice floats in a beaker of water and the entire system is at 0 degrees Centigrade. Just enough heat is supplied to melt the ice cube without changing the temperature of the system. Does the water level in the beaker rise, fall, or stay the same?

A man walking at night along a sidewalk at a constant speed passes a street light. As his shadow lengthens, does the top of the shadow move faster or slower or at the same rate as it did when it was shorter?

Which is worth more: A pound of $10 gold pieces, or half a pound of $20 gold pieces?

A piece of solid iron in the form of a donut is heated. Will the diameter of the hole get larger or smaller? (An oldie but goodie.)

A trucker stopped his panel truck before driving onto a bridge that he thought would not hold up the weight of his vehicle. He began beating the sides of the truck with his hands. He was carrying 200 pigeons, and his pounding would make them all fly around inside the truck. He thought that if the pigeons stayed in the air, the vehicle load would decrease by the weight of the birds, and he could drive over the bridge with less weight. If the truck's load compartment is air tight, will things behave as he believes?

Are you or one of your colleagues teaching fluid mechanics this semester? Will piping systems be covered? If so, it is probably important to discuss pipe specifications. I am not referring to ANSI B36.10-79, published by ASME. I am referring to those unofficial specifications that should be known and communicated. The specifications are appropriately written with dual units; that is, where dimensions are given in engineering units, the corresponding SI dimension is provided in parentheses. Here they are:

Pipe Specifications

1. All pipe is to be made of a long hole, surrounded by the pipe material which is centered around the hole.

2. All pipe is to be hollow throughout its entire length.

3. The O.D. of all pipe must exceed the I.D., otherwise the hole will be on the outside.

4. All pipe is to be supplied with nothing in the hole so that a fluid can be put inside at a later date.

5. All pipe over 500 feet (152 m) long must have the words "long pipe" clearly painted on each end so that the fitter will not substitute it for short pipe.

6. Pipe over 2 miles (3200 m) long must also have these words painted in the middle so that the fitter will not have to walk the full length of the pipe to determine if it is long pipe or not.

7. All pipe over 6 inches (0.15 m) in diameter is to have the words "large pipe" painted on it so that the fitter will not substitute it for small pipe.

8. All acid proof pipe is to be made of acid proof material.

9. All pipe is to be supplied without rust (if steel) or other contaminant, because these can be more easily applied at the jobsite.