CHARLESTOWN — Like the chemicals and forces at work in their show, Maryland Science Center science educators Hannah Dickmyer and Rachel Sweeney acted and reacted to one another throughout the science experiments they demonstrated during a June 6 assembly at Charlestown Elementary School.
The “Science Unscripted” show tours the state of Maryland and changes with every performance as volunteers from the audience pick a card at random, each with a different science topic written on it to be investigated further.
Before tackling any science, however, Sweeney and Dickmyer highlighted the importance of practicing safety when doing science. At CES, safety came with a fire extinguisher, goggles, gloves, and safety cones and chains that the young audience members remained seated behind until volunteers were called on and given special permission to join the science educators at the front.
But most importantly, safety came in the form of an adult safety partner, with Dickmyer and Sweeney looking after one another and their inquisitive science volunteers during the show.
“We want you to do science when you’re at home, but we ask that you grab an adult safety partner first who knows that science is happening before you do any science because it will help keep you safe,” Dickmyer said.
One by one, Sweeney and Dickmyer called up volunteers from the audience who were staying seated, quiet and well-behaved during the show.
In the first demonstration of the show, the science educators took on the topic of sound.
“Sound travels through the air in waves, but maybe not waves like you would expect. Not waves like in water. They’re called ‘pressure waves,’” Dickmyer explained.
Dickmyer and Sweeney filled a tube with a flammable liquid and then ignited it so the audience could see and hear how sound travels.
When lit by the fire, the inside of the tube elicited a short boom. Then, Sweeney and Dickmyer repeated the experiment with a longer tube, creating an even deeper sound because a longer tube allows for a longer wavelength, which results in a lower frequency.
In another demonstration, Dickmyer and Sweeney showed how air flows between different pressures.
When a volunteer blew directly into a long plastic bag for 10 seconds, she was able to fill most of it.
But when Sweeney blew into a bag from farther back, she was able to fill it in one strong puff — a feat which she explained was do to a concept called the Bernoulli principle, named after Swiss mathematician and physicist Daniel Bernoulli.
“The Bernoulli principle says that fast moving air has lower pressure,” Sweeney said. “Whenever there’s an imbalance of pressure — if there’s high pressure over there and low pressure over there — air will always go into the area with lower pressure. I did one really fast puff into the bag, and because it’s moving so fast I create a low pressure zone which then sucked in air from the rest of the room.”
Dickmyer and Sweeney also showed the presence of air pressure when they had that same volunteer step into a trash bag and sucked the air out of the bag with a vacuum cleaner.
After the volunteer shared that the bag felt like it was squeezing against her, Sweeney said this was because she was feeling the weight of air pressure against her.
“That squeezing that you felt was actually just the air inside this room pushing up against you because we created an air pressure imbalance,” Sweeney said. “There’s no more air inside the bag, so all that squeezing and all that pressure you felt was just the 15 pounds of air pressure on every square inch that’s there all the time.”
Dickmyer and Sweeney performed several other experiments such as using liquid nitrogen to make the air molecules in a balloon animal become closer together, allow the balloon to be crushed without popping, and then have the balloon return to its original shape after the air molecules inside dispersed.
They also used a Van der Graaf generator to show static electricity causing Dickmyer’s hair to get frizzy — although the day’s humidity prevented her hair from standing completely on end.
With the hour drawing to an end, Dickmyer and Sweeney concluded “Science Unscripted” in the only way a science show can: with a bang — or three to be exact.
Sweeney and Dickmyer brought three balloons with them. But rather than using balloons filled with helium — which Sweeney explained “doesn’t like to do chemical reactions” because it’s an inert gas — they filled the balloons with hydrogen, which lends itself more to combustion reactions.
Dickmyer held a flame up to the balloons, each eliciting a loud boom as it popped and creating a different flash of light caused by the chemicals that joined the hydrogen inside.
With the show meeting its close, the young audience members prepared to continue practicing science with safety, responsibility and curiosity.