I am a HS student in China preparing for a regional Young Physicist Tournament even. We are very puzzled about why would there be such movement. We would be grateful to see any inspiring replies. Thank you!
Update: As I dig through the relevant literatures (such as a royal soc. proc. A paper) on the 'Bristle-Bots'(BBots), it becomes clear why and how brushes mounted with eccentric motors attain locomotion, both qualitatively and quantitatively. HOWEVER, I am still quite puzzled by the problem to quantitatively predict the movement of an unmodified brush placed on a vibrating surface. The primary obstacles are as follows: 1. Contact force calculation (bristle and surface) 2. Internal forces within the brush system, so as to understand the deformation and change of the center of mass 3. Motion function of time derivation (The Sum Up...)
Thanks for reading the post!