Demos by PIRA

  3A10.10Ball on string mounts on blackboard and pivots on lower rod.
  3A10.10Simple pendulum: Ball on a string.
  3A10.14Four pendulums on rod: Same mass, different lengths.
  3A10.17Four pendulums on rod: Same length, different masses.
  3A10.30Torsion pendulum with removable weights.