It was one of the most iconic experiments and public performances in the recent history of the University: what happens when you place liquid nitrogen in a container filled with 1,650 ping-pong balls?
The answer was provided by Dr Roy Lowry, Associate Professor in Physical Chemistry, who transformed Roland Levinsky Crosspoint into the Kennedy Space Centre back in the summer of 2015 and demonstrated to a gathered audience the explosive results.
Using video cameras, the team captured the moment as hundreds of ping-pong balls were fired high into the atrium. The footage was later released via the University鈥檚 website and was requested by several media outlets.
Now, nearly four years on, researchers in Brazil and Germany, partly inspired by that video 鈥 and using images supplied to them by Dr Lowry 鈥 have revealed the underlying physics to a peculiar phenomenon that occurs at the moment of lift-off.
Published in the American Journal of Physics the research paper explains why the container barrel can be seen to move upwards at the same time as the balls, something counterintuitive to Newton鈥檚 third law which states 鈥榝or every action, there is an equal and opposite reaction鈥.
A combination of 鈥榞ranular jamming鈥 and Coulomb鈥檚 friction is the reason why the container lifts off the ground, rather than it being forced backwards or compressed in upon itself.
鈥淲hile the original event was designed to enthuse the next generation of scientists, it is fabulous to see that it also inspired the current generation to think more deeply about an apparently simple system,鈥
said Dr Lowry, a Member of the Royal Society of Chemistry and Fellow of the Higher Education Academy.
鈥淎nd now it鈥檚 gone full circle as their paper has inspired an article in a science magazine for the public!鈥
Indeed, it has now looped back to 麻豆传媒, as the Brazilian media have requested images from the original experiment to illustrate the story.
鈥淚 became a chemist thanks to a teacher who regularly showed us chemistry as well as taught it,鈥
added Dr Lowry.
鈥淚鈥檓 a firm believer in the power of the visual to generate passion for a subject and we need passionate problem solvers in today鈥檚 world.鈥
View the paper 鈥樷 in the American Journal of Physics.
