from the To-see-a-world-in-a-grain-of-sand-and-corn-dancing-on-a-stove dept.
Some dynamic systems can develop multi-periodicity, meaning that some parameter, such as a mechanical oscillation, can switch between different vibrational frequencies or amplitudes. For instance, a small-scale disturbance is coupled into a large-scale one.
This has been observed in muscle motion, laser stability, seismic motion, etc, and there is much to understand about these couplings in chaotic systems. Initiated by an apparent diversion from pandemic boredom, Promode Bandyopadhya noticed that when shucked cobs of corn were placed on a glasstop hotplate, the cob oscillates autonomously about three axes with varying amplitudes and frequencies that shifted randomly with time. He videoed ears of corn as well as a number of other smooth fruits on a hot surface and extracted their motion over time. His results are summarized in a tour de force of mechanical dynamics in a Nature Scientific Reports paper. He observed that corn cobs roll, pitch, and yaw, but green chilies, blueberries, tropical berries, red grapes, oblong grapes and grape tomatoes only roll and yaw.
Autonomous thrust oscillations are difficult to design in a laboratory, however we have discovered that the seven types of fruit offer a new test bench.
Details and videos of his dynamical systems kitchen laboratory observations are provided as a Google Drive Link.
Promode R. Bandyopadhyay. Multistable autonomous motion of fruit on a smooth hotplate [open], Scientific Reports (DOI: 10.1038/s41598-021-03859-8)