Turning effects and a clock-spring
Springs tend to return to their original shapes when they are stretched, compressed, or, in this case, turned.
Apparatus and materials
Clock-spring, large, mounted on a board at the spring centre
Retort stand, boss, and clamp
Loads to be hung from spring arm, e.g. thread
Health & Safety and Technical notes
If loads slip along the arm of the spring, use small pieces of modelling wax or Plasticine to hold them steady.
a Clamp the board vertically to a retort stand, for convenience of demonstration.
b Hang loads from the arm of the spring to apply force to it. The spring tends to return to its original shape, and provides a force which opposes the applied force.
c Hang different loads at the same place on the arm, to show that weight is a factor in the size of the turning effect due to the load.
d Hang a load at different positions along the arm, to show that distance is a factor in the size of the turning effect due to the load.
1 The force due to a spring, in opposition to an applied force, is a 'restoring force'.
2 An additional demonstration could show a screw jack (or a rotating chair with a spiral thread), raising a load by pushing on the arm of the screw jack with a very small force. The longer the arm, then the smaller the force.
This experiment was safety-checked in October 2004