The Magnetic Levitation, the Friction Oscillator, and the Little Bang

ACS Team of Young Physicists Wins Gold at the National Round of the IYPT

Atanas Iliev, Nikolay Mitev, Todor Kiurkchiev and Gergana Peykova

“A stationary cylindrical vessel containing a rotating plate near the bottom surface is partially filled with liquid. Under certain conditions, the shape of the liquid surface becomes polygon-like. Explain this phenomenon and investigate the dependence on the relevant parameters.” In turn, “Under certain circumstances, the “flea” of a magnetic stirrer can rise up and levitate stably in a viscous fluid during stirring. Investigate the origins of the dynamic stabilization of the “flea” and how it depends on the relevant parameters.”

These are just two of the twelve problems the four ACSers of team “Little Bang” have been working on over the past months, in order to defend their solutions at the national round of the International Young Physicists’ Tournament last weekend in Kyustendil. The meticulous preparation, sleepless nights and excellent team cohesion of seniors Nikolay Mitev (team captain) and Gergana Peykova, junior Todor Kiurkchiev and tenth grader Atanas Iliev took team “Little Bang” to the top, both at the preliminary and final physics “fights”, and brought them, deservedly so, gold medals.

Here is what Nikolay shared: “The friction oscillator problem is among my favorites. The basic case is relatively easy to solve – it’s a second-order differential equation. While it may not sound too easy, compared to the other solutions, it’s not much of a challenge. The condition doesn’t point out which way the cylinders rotate and that changes the outcome significantly. Theoretically speaking, once you write out the solution it is expected that the massive object will begin to oscillate harmonically, as the cylinders rotate inwards. If they spin outwards, the theoretic solution points to a hyperbolic function which doesn’t indicate a clear definition of what happens between 0 and 1, and in practice, the object falls. On paper, the solution set very clear expectations for us from the experiment, but once we built the set-up, we were quite surprised. Apart from vibrating, the massive object started spinning, which was caused by forces not predicted by the theoretical model. With changes in the radius and the rotation speed of the cylinders we achieved effects testifying to brand new phenomena. It was one thing I expected from the theory and the experiment showed something very different. Figuring out why was quite interesting and fun for me to try.”

Participation in all rounds of the IYPT is a team effort, which is crucial to success. During the active physics “fights” each of our contestants takes on a specific role, they keep a close contact and prepare analyses, presentations, moderation ideas, and discussion points in real time. Nikolay said: “Our team is great, I’ve known each of them well for a long time and they are all big professionals in physics and other fields as well. For example Todor is both a physicist and an astronomer. Not only does he have international competition and problem-solving experience, but he is also very strong in defending his ideas in a convincing way. Gergana is a wonderful physicist and theoretician. She conducted the experiment with the magnetic levitation and spent days in the physics lab, filming on a cell phone the stirrers spinning and levitating in the viscous liquid. None of the other competing teams had taken the time and effort to do so, to document all measurements, and to process all the data in such a precise and professional way. Atanas is a brilliant mathematician. He had developed ten slides worth of theory on a single problem, with all the equations, matrixes, and Lagrangians in order to describe the motions of a pendulum in five degrees of freedom. When he brought over his solution, we were in awe. He had written a computer simulation which was precise in predicting what would happen, and we observed a correlation between the data and the experiment, which was marvelous. It appears the four of us have figured out the right formula, in order to reach the final and win it.”

“I congratulate our students for their exceptional teamwork and months of consistent efforts on theoretical and experimental research on the problems.” – commented Dr. Krasimira Chakarova, ACS Physics and Astronomy Teacher, Science Department Chairperson and team supervisor.