Fred Schaal [Lane Tech HS]

More on the egg and the bottle. He was thinking of way to get the egg out of the bottle that is was sucked into. Starting a fire so as to build pressure to push the egg out?? If the pressure is too great the bottle will explode??? Jet-x rocket fuel...maybe the model rocked fuel that was around a while back could be lit and push the egg out.

Someone commented that just blowing into the bottle might give enough pressure to force the egg out?

Earnest Garrison [Chicago Vocational High School]

He brought in a hi-tech YO-YO. How could an old thing as yo-yo be made high tech? The answer to the new yo- yo's is that they have a clutch operated by a speed regulator that allows you to "walk the the dog", and when the speed drops the clutch engages and up comes the yo-yo. Also as a hi-tech feature, they have lights that flash and a sound that is made; some even depend on speed. It is surprising that such an old concept is still enticing the youth.

Porter made a comment about the yo-yo variation called the diabolo, which consists of two sticks and a string with which you spin a spool of a certain size and weight. Once you get it to spin fast enough you can throw it in the air, and if you are good [like me! -PJ] you can catch it back on the string! Amazing, but not impossible! The game was invented by the Chinese over 2000 years ago, and brought to Europe by French and English expeditions, and given the name diabollo [ancient Greek, "through throw"]. Pictures and details can be found on the following webpage: http://www.juggling.org/help/circus-arts/diabolo

Porter Johnson [IIT]

Porter took off on the use of the calculator and commented about not rounding off! By using integers and keeping the calculation to as many places as possible we may get an answer that will result in integers. If you round off the answer will be an decimal, and hide the fact that the answer from a problem starting with integers will be integers. You may not want to round the working numbers in a calculators to a few significant places and thus hide some of significance of the answer. The example consisted in calculating the area of a triangle with vertices at integer-valued x- and y-coordinates. The area of the triangle, which will come out as either an integer or half-integer, can be computed geometrically by enclosing a rectangle around the triangle, and calculating the area of the rectangle and the other right triangular pieces. Simple, non??

Earl Zwicker [IIT Professor Emeritus]

Earl showed a device with two disks of different mass between springs. The device has a timer that when the springs were compressed it would stay for about 10 seconds and release the spring. If the lower mass disk was down at the table and the spring accelerated the higher mass, thus the assembly would jump, and the next trial the larger mass was on top-being accelerated; which condition would the assembly jump higher?

It was hard to tell, but seemed that with the the larger mass on top it would jump a little higher???