1M40.12 - Tension in a Pendulum String

Code Number:
Demo Title:
Tension in a Pendulum String
Potential to Kinetic Energy, Simple Harmonic Motion
Area of Study:
0 to 100 Newton Spring Scale, Heavy Pendulum Bob and Cross Rod with Hook, Support Stand, 1 and 2 kg Masses, 1 and 2 lb. Weights, Special Hook to Hang Scale and Support Stand On.

Video and Editing Credit: Jonathan M. Sullivan-Wood.

Attach the desired cross rod with the pendulum to the support assembly and make sure that it is secured tightly. Hang the support assembly from the Newton scale and the scale from the special hook clamp. Add 6 kg of mass to the support assembly.   This combination has been picked to give a good time scale for the spring deflection. The pendulum will appear to be heavier at the bottom of its swing and lighter at the top of its swing in relation to its rest mass.

  • Ben Szapiro, "Simple-Pendulum Lab with a Twist", TPT, Vol. 40, #3, Mar. 2002, p. 158.
  • James O'Connell, "Tension in a Pendulum String", TPT, Vol. 40, #1, Jan. 2002, p. 24.
  • Raymond E. Benenson, "Weighing an Accelerating Kilogram-Mass with a Spring Scale", TPT, Vol. 32, #5, May 1994, p. 284.
  • Robert Ehrlich, "2.11, Weighing a Swinging Pendulum", Why Toast Lands Jelly-side Down, p. 36
  • Robert Ehrlich, "F.10, Whirling a Water-filled Can in a Vertical Circle", Turn the World Inside Out, p. 75.
  • David Kutliroff, "Centripetal Force Demonstration with a Pendulum, 101 Classroom Demonstrations and Experiments for Teaching Physics, p. 93.

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