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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
  video  - Center of Mass of Virginia
  video  - Center of Mass Toys
 Stacking Blocks
  video  - Stability Track
  photos  - Tension in a String
 Rope and Three Students
  photos  - Knot in Static Equilibrium
 Force and Tension
 The Roman Arch
 Rotational Equilibrium
  video  - Giant Yo-Yo
 Applications Of Newton's Laws
 Work and Energy
 Rotational Motion
 Properties of Matter

Rope and Three Students


To demonstrate the effect of a small force through a large distance.


Two large students pull on the ends of a rope and a small student deflects the rope in the middle pulling the large students together.

Have two powerful students stretch the rope between them and put as much tension on it as they can. Have a frail student come to the middle of the rope and quickly press down with one finger. The large and powerful students will be pulled off balance as they try to unsuccessfully prevent the center of the rope from being deflected onto the floor.

Reference below: The Physics Teacher 9, 148 (1971)


  • Diminutive and Frail Student
  • Huge and Powerful Student
  • Long Piece of Strong Rope (approx. 50 ft.)