The Ups and Downs of Convection
The Sioux City Community School District -- which includes Sioux City's North, East and West middle schools -- is one of 20 NASA Explorer Schools that designed an experiment that was conducted on a reduced-gravity flight. Teachers ran the experiments on NASA's "Weightless Wonder" aircraft. The aircraft flies in a roller-coaster-like path. When the plane climbs up, passengers can feel almost twice as heavy. Then the plane descends toward the Earth, letting passengers experience weightlessness. This process is repeated multiple times during the flight.
Sixth-grade students in Mitch Rorris' science class wanted to know how changes in the amount of gravity would affect convection, the flow of a liquid or gas. To find out, the students built an experiment.
Their experiment used two cylinders -- one heated and one cooled. A connecting tube near the bottom of the cylinders allowed air to flow between the cylinders.
The experiment was conducted in class using ice to cool the air and hot water to heat it. In the heated cylinder, the air expanded and rose to the top. In the cooled cylinder, the air contracted and settled to the bottom. The cool air flowed into the heated cylinder through the connecting tube.
A slow-burning stick was placed into the cold tube to make smoke so the students could see the air movement. Students observed the smoke fall in the cooled cylinder and flow into the heated cylinder through the connecting tube. Then the smoke rising to the top of the heated cylinder showed the convection current.
Rorris and other Sioux City teachers performed the same experiment on the Weightless Wonder. The experiment on the Weightless Wonder used dry ice, to make the air even colder, and a light bulb to produce heat. The teachers on the aircraft used computers to track air movement by measuring the temperature in the cylinders as the gravity on the plane changed. Students analyzed the data later.
Students hypothesized that as the gravity increased, the air would slow down and compress at the bottom of the chamber. And, as gravity decreased, the air would release and spring upward.
"Sure enough," Rorris said, "there's an indication that that's pretty much what happened. It's only one test ... but it indicates that the kids were right."
Rorris said running the experiment in microgravity was exciting. "The experience gets me fired up," Rorris said. "It really gets me going again. When the kids see an instructor that's really into it, it spreads."
Three other teachers were part of the flight team. Julie Sweeney and Anthony Gaul are sixth-grade teachers. Ryan Reinking teaches eighth grade.
Rorris couldn't find the words to describe the unique experience. "When you go from two-g's to having that release in microgravity, it's just unbelievable," he said.
The NASA Explorer Schools project is one of many NASA projects to prepare the next generation of scientists, engineers, astronauts and others. NASA is working to excite today's students about science, technology, engineering and mathematics so they can carry on NASA's mission in the future.
The Ups and Downs of Water Droplets
The Ups and Downs of Liquid Density
Reduced Gravity Student Flight Opportunities Program →
NASA Explorer Schools →
NASA Education Web Site →
Heather R. Smith/NASA Educational Technology Services