A bar of mass m is suspended horizontally on two vertical springs with the force constants k and 3k. The bar bounces up and down while remaining horizontal. Find the period of oscillations of the bar. Neglect the mass of the string that connects the springs and the friction between the string and the pulley.

We received a large number of solutions from all over the world for our September Challenge, Slipless in Seattle. We are pleased to recognize the following contributors:

  • Sharmila Balamurugan (undergraduate student, Women's Christian College, Chennai, India)

  • Dave Bittel (Bristol Eastern High School, Bristol, CT)

  • Phil Cahill (Lockheed Martin Corporation, North Yorkshire, United Kingdom)

  • Bartley L. Cardon (retired, MIT Lincoln Laboratory, South Portland, ME)

  • Juan Carlos Criado Alamo (student, University of Granada, Spain)

  • Don Easton (Lacombe, Alberta, Canada)

  • Fernando Ferreira (Universidade da Beira Interior, Covilhã, Portugal)

  • Josh Gates (Tatnall School, Greenville, DE)...

Supplementary Material

Supplementary materials- zip file
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.