Created by Dale Olive and Randy Scoville
Future Flight Hawai`i instructors
Demonstration at a glance:
A paper tube is lit from the top and burns down to the tabletop where the ash suddenly rises high into the air.
Obtain the tissue from old themofax or ditto masters which protects the carbon on the masters. Tape this into a tube with a small piece of tape on the top and bottom. Light the tube from the top and support it from falling over as it burns. This works best in a room with still air. Very cheap tissue paper is supposed to work for this also but I have never been able to find a brand that works.
As the paper burns down the almost weightless ash remains. When the ash pile is light enough it gets caught on the rising current of hot air from the burning paper. As we all know, hot air rises because it is less dense than cooler air (have you ever heard of a "cold air balloon"?) This rising air current is known as a convection current. It's an important concept in science explaining everything from what creates wind to why the continents move.
Another convection demonstration can be done with a device called a convection box. This is small box that has two holes cut out on either end to which a toilet paper tube is inserted into each. Under one of the holes a small lit candle is placed. This causes the air to rise over this toilet tube chimney. Air is then drawn into the other tube causing a convection current. These can be bought from supply catalogs or can be made quite easily. To see what's going on in the box I cut the side out and tape a transparency over the opening.
Communications: Hawaii Space Grant Office
This activity is featured in Future Flight Hawaii, a K-12 Education Project of Hawaii Space Grant Consortium.
FEB 27 2001.