Minimum Distance That a Pendulum Bob Wraps Once Around a Post

• Ping Jia ^[2] ; Hong Li ^[2] ; Bixing Yan ^[1]
  1. [1] New York University

     New York University

     Estados Unidos

     
  2. [2] Suzhou Science and Technology Town Foreign Language High School, Suzhou, Jiangsu, China
• Localización: The Physics Teacher, ISSN 0031-921X, Vol. 62, Nº. 7, 2024, págs. 548-549
• Idioma: inglés
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• Resumen

  • An intriguing simple pendulum issue was raised in a Physics Challenge in The Physics Teacher.1 We generalize the original challenge (in which the pendulum is released from its initial horizontal orientation) by allowing the initial angle of the pendulum to vary as follows. The ball is initially held in a position where the string is taut and at an angle of α below the horizontal plane of the fixed point. Once released, the ball travels in a circular path with air resistance assumed to be negligible.2 A bottom post is placed at a distance of l beneath the fixed point, perpendicular to the motion plane of the ball. When the ball reaches the lowest point of its trajectory, the string meets the bottom post and may wrap around it. What is the minimum distance l that allows the ball and string to wrap once around the bottom post? In this paper, we also describe an experimental approach to investigate this issue.