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Code Number: 1N20.10
Demo Title: See-Saw Center of Mass
Condition: Excellent
Principle: Conservation of Momentum/Center of Mass
Area of Study: Mechanics
Equipment:
2" X 4" Fulcrum, Pasco Dynamics Track, and Pasco Dynamics Carts with Compressible Springs.
Procedure:
Balance the Dynamics track on the 2 X 4 fulcrum. Place two carts on the track in a position such that the whole system is balanced on the fulcrum. One of these carts has a compressed spring. When the spring is released the carts will spring apart and travel to the ends of the track. As they are traveling, the whole system is still in balance. This will remain true even if more mass is added to one cart.
References:
- Fritjof E. Christensen, "Toward Improved Apparatus and Better Experiments", TPT, Vol. 12, # 9, Dec. 1974, p. 564.
- Herbert H. Gottlieb, "Balanced Dynamic Carts", TPT, April 1967, p. 173.
- Robert Ehrlich, "F.17, Ball Rolling on a Balanced Beam", Turn the World Inside Out, p. 84.
- David Kutliroff, "57, Motion of Center of Mass Is Not Affected by Internal Forces", 101 Classroom Demonstrations and Experiments For Physics Teachers, p. 127.
- Borislaw Bilash II, David Maiullo, "Seesaw Carts", A Demo a Day: A Year of Physics Demonstrations, p. 156.
- George Freier, "A New Reaction - Cart Demonstration", AJP, 33 # 1, XXV, Jan. 1965