Rattleback bet

• Autores: Steve Dail
• Localización: The Physics Teacher, ISSN 0031-921X, Vol. 49, Nº. 5, 2011, pág. 316
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • A neat twist to the �rattleback�1or �celt� demonstration was revealed to me after a �bet� with one of my AP® Physics students.2I asked the class to try to explain what is responsible for the spinning piece of plastic to suddenly reverse its direction of spin. Some thought about air friction, others discussed the offset center of gravity. There are many online sources with detailed explanations, as well as in TPT,3so I will not try to explain it here, but I felt that friction between the rattleback and the table definitely played a major role in the explanation. My student disagreed. The next day my student showed up to class with a small container of Vaseline and declared, �We will settle this right now. Lets grease up a lab table and spin the rattleback and see what happens.� (I wish allmy students were this curious!) First, we spun the rattleback several times on a clean table to see the interesting spin reversal. Then after applying a thin layer of Vaseline to the table, we spun the rattleback. Try it yourself (or email me) to see who won the bet!