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Code Number: 1D40.50
Demo Title: Air Track Pendulum
Condition: Good
Principle: Center of Mass
Area of Study: Mechanics
Equipment:
Air track, air track pendulum, large pendulum in moving frame.
Procedure:
Start the pendulum swinging and then push the whole cart and pendulum system down the air track. The car will seem to start and stop as it moves down the track. However, if you look at it with videotape or video capture you will see that the center of mass of the whole system moves at a constant velocity.
The large center of mass pendulum is in the basement. Start the mass swinging and depending on when you release the system, the system will oscillate in place or will travel across the room in what seems to be jerky movements. If you video this movement you will see that the center of mass of the system travels smoothly at a constant velocity.
References:
- Tarek A. Elsayed, "Interpreting Recoil for Undergraduate Students", TPT, Vol. 50, #4, Apr. 2012, p. 209.
- Margaret Stautberg Greenwood, "Conservation of Momentum and the Center of Mass of a Cart - Truck System", TPT, Vol. 25, # 6, p. 370, September 1987.
- Akio Saitoh, "Conservation of Momentum - Walking the Boat", TPT, Vol. 23, # 5, p. 316, May 1985.
- W. Klein and G. Nimtz, "Inelastic Collision and the Motion of the Center of Mass", AJP, Vol. 57, #2, Feb. 1989, p. 182.
- Mp-1: Freier and Anderson, A Demonstration Handbook for Physics.
- M-486: "Swivel Hips - Pendulum on Cart", DICK and RAE Physics Demo Notebook.
- M-125: Richard Manliffe Sutton, Demonstration Experiments in Physics.