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The gravity carousel

The gravity carousel
Materials and mounting
instructions:
  A support basis, the cover of a cylindrical box, a hexagonal pencil with sharpened point, nut and counter-nut with inner diameter to fit the pencil, a spool, a wood arm, a wood block (about 5x10x15 cm3), a small pulley, a thin robust string about 1 m long, a heavy nut. Make a hole in the centre of the cylindrical cover (that will serve as carousel platform), insert in it the pencil trying to obtain a tight fit, fix the platform at a distance of about 5 cm from the point of the pencil using the nut and counter-nut. Make a hole near one end of the wood arm with a diameter larger than that of the pencil. Fix the wood block vertically near the edge of the support basis; on its top fix the pulley and, on the opposite side, fix the the wood arm. Insert vertically the pencil through the hole at the opposite end of the wood arm and insert its upper part in the spool with a tight fit. Wind the string on the spool and tie the heavy nut at the other end.
How to play:   Put the support basis close to the edge of a table, thread the free string end on the pulley and let the heavy nut descend: it will start slowly and the carousel will turn more and more rapidly.
Physics:  
  • different forms of energy:position, translational motion, rotational motion,
  • energy transfer: from the heavy nut to the platform (it can be varied by loading the platform or using a heavier or a lighter nut),
  • energy storage: as position energy of the nut,
  • force, interaction and energy: the gravity force on the nut sets the nut in motion, the elastic force of the string transfers the motion to the carousel.
Educational aspects:  
  • discover different forms of energy (Eb),
  • discover transfers of energy (Ec),
  • experiment storage of energy (Ed),
  • identify the force needed to start the motions of the nut and of the carousel (Fa),
  • analyse the relation between the force which determines the motions and the energy (Ea),
  • compare with your expectations.
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Last modified: Thu Nov 16 08:58:23 CET 2000