1M40.30 - Gravity Rail

Code Number:
Demo Title:
Gravity Rail
Conservation of Energy
Area of Study:
'U' rails of different shapes, steel ball.

Clean the tracks and set up so that they are level.  Care should be take to ensure that the track rails are not damaged or bent in any way.

When operating properly the large "U" rail should go for up to 10 minutes.

  • Yau-Jong Twu, "From Rolling Without Slipping to Sweet Spots", TPT, Vol. 58, #3, Mar. 2020, p. 218.
  • Paul Hewitt, "Figuring Physics: Direction of Friction", TPT, Vol. 49, #1, Jan. 2011, p. 7.
  • Paul Hewitt, "Hewitt's Response", TPT, Vol. 46, #2, Feb. 2008, p. 70.
  • Christopher LaSota, "Comment on 'Rolling Ball' (Figuring Physics, Dec. 2007)", TPT, Vol. 46, #2, Feb. 2008, p. 70.
  • Paul Hewitt, "Figuring Physics: Rolling Ball", TPT, Vol. 45, #9, Dec. 2007, p. 534.
  • M. W. Ramsdell and D. P. Wick, "Predicting Turning Points for Toy Cars", TPT, Vol. 43, #7, Oct. 2005, p. 442.
  • Paul Hewitt, "Figuring Physics: Plate on the Earth", TPT, Vol. 40, #8, Nov. 2002, p. 456.
  • Alan Cromer, "An Unusual Rolling−Sphere Phenomenon", TPT, Vol. 34, #1, Jan. 1996, p. 48.
  • Rod Cross, "Sliding and Rolling Along Circular Tracks in a Vertical Plane", AJP, Vol. 91, #5, May 2023, p. 351.
  • Dale R. Blaszczak, "The Roller Coaster Experiment", AJP, Vol. 59, #3, Mar. 1991, p. 283.
  • G. D. Freier and F. J. Anderson, "Mr-2", A Demonstration Handbook for Physics.
  • Jodi and Roy McCullough, "Work and Energy with Hot Wheels Car", The Role of Toys in Teaching Physics", p. 4.18.
  • Borislaw Bilash II and David Maiullo, "Galileo, Energy Conservationist", A Demo a Day: A Year of Physics Demonstrations, p. 91.
  • Robert Ehrlich, "Ball in a Parabolic Potential Well", Why Toast Lands Jelly-Side Down, p. 130 - 131.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.