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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Motion In One Dimension
 Motion In Two Dimensions
 Newton's First Law
 Newton's Second Law
 Newton's Third Law
 Statics Of Rigid Bodies
 Applications Of Newton's Laws
 Brachistochrone curve
 Cavendish Balance Model
 Gravitational field model
 Work and Energy
 Rotational Motion
 Properties of Matter

Brachistochrone curve


To demonstrate that the curve of fastest descent between two points that is covered in the least time by a point-like body under the action of constant gravity is not a straight line.


Place two balls/pebbles on top of the apparatus and hold them with a plastic shim. Release the balls and watch the ball following the straight line track land in the can later than the one following the cycloid. The can bang makes for a better stop watch.


The red plastic holder shim is inside the "Drum" can along with the balls.

Instead of using the can as a "stopwatch", one can place the track apparatus on the West end of Rm. 203 big bench, clamp 2x4 and foam to other end to catch the balls, allow balls to roll across bench to show curved track comes off first (quicker) and both balls end up with same speed (kinetic energy is the same).


  • Brachistochrone curve apparatus