Year 12 Mechanics Conservation of Energy Experiment:


  • The purpose of this experiment is to demonstrate the conservation of energy using a large mass on the end of a string.


  • String, rope etc.
  • Large mass / ball etc.
  • Support hook with open space.


  • Connect a large mass, via a string (rope) to a secure hook.
  • Get a student to hold the mass against their cheek
  • Ask student to stay perfectly still
  • Mass will come back to the exact same starting place

Pitfalls / causes of error

  • Caution should be used if the center of mass of the object being used is not in the center of the object. I once used a 5kg slotted mass which was released side on, and then returned front on. The center of mass returned to the same position, but due to the non-symmetrical nature the mass hit the student..... it does not make for a good demo!


Click to watch the (9mb 1.54min) Faith in Physics video created by New Zealand Physics Teachers' Resource Bank hosted by Victoria University of Wellington

Model data:


References / other comments:

  • This is ALWAYS best done in real life!