Demonstrations

Central Forces - Centripetal Force

Code Number :	1D50.50
Disclaimer :	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: U of Iowa Disclaimer All RIghts Reserved.
Condition :	Good
Principle :	Forces Due To Circular Motion
Area of Study :	Mechanics
Equipment :	Pasco Centripetal Force App., Weight set, Cenco Centripetal Force App., Variable Speed Rotator, Strobe Light.
Procedure :	Hang weights on the pendulum on the Pasco rotator until it hangs straight up and down. Record that weight and then remove. Now, rotate the apparatus until the pendulum hangs straight down again and record the rotation rate. The force applied by the rotation rate is the same as the static force applied by the weights. Attach the centripetal force app. to the variable speed rotator. Increase the rpm's on the rotator until the mass in the centripetal force app. extends the spring to the end of the app.. Using the strobe light will provide the stop action viewing necessary for this step. Next hang the centripetal force app. from a hook and hang mass onto the app. until you find how much mass it takes to extend the spring the same amount it was extended when the app. was rotating. The Max-Air plane is a battery power device that can be connected to a tether in the lecture rooms. LR70 is probably the easiest room to do this in. Centripetal force data can be obtained when the plane is flying in a circle while connected to a scale or force sensor. Charge and discharge the batteries in the plane once. After that, for every second that you charge the plane battery, you will get one second of run time from the plane motor. Charging for 20 seconds or less seems to work well in LR70.

References

David Chesnut, "Centripetal Force Using a Band Rotator", TPT, Vol. 44, # 9, Dec. 2006, p. 619.

Donald F. Collins, "Centrifugal Icicles and an Inertial Paradox," TPT, Vol. 42, # 2, Feb. 2004, p. 79.

Ronald Bryan, "Some Examples of Centripetal Acceleration", TPT, Vol. 40, # 1, Jan. 2002, p. 32.

Roger F. Larson, "Centrifugal Force and Friction", TPT, Vol. 37, # 7, Oct. 1999, p. 426.

"Figuring Physics," TPT, Vol. 37, # 8, p. 475, (Nov. 1999).

Ken Altshuler, "Inexpensive Rotating - Arm Device for Angular - Motion Labs," TPT, Vol. 36, # 7, p. 424, (Oct. 1998).

Alvin H. Bachman, "Comments on Radial Acceleration Derivation", TPT, Vol. 34, # 5, May 1996, p. 260.

David W. Kraft, Lloyd Motz, "Geometric Derivation of Radial Acceleration Magnitude", TPT, Vol. 33, # 8, Dec. 1995, p. 565.

Joe Bunn, Jay Smith, "Measure Centripetal Force for Under $3", TPT, Vol. 32, # 6, Sept. 1994, p. 380.

Volker Thomsen, "Two Problems in Mechanics", TPT, Vol. 32, # 2, Feb. 1994, p. 111.

Bill Wedemeyer, "Centripetal Acceleration - A Simple Derivation", TPT, Vol. 31, # , Apr. 1993, p. 283.

"PSSC Physics Rediscovered", TPT, Vol. 31, # 6, Sept. 1993, p. 327.

Keith Fillmore, 'What Goes Around Comes Around", TPT, Vol. 31, # 9, Dec. 1993, p. 518.

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Walter Connolly, "Circular Motion and An Inverse Square Machine", TPT, Vol. 27, # 2, Feb. 1989, p. 108.

Frank Butcher, "Circular Motion Studies with a Toy Airplane", TPT, Vol. 25, # 9, Dec. 1987, p. 572.

Bill Franklin, "More on Toy Airplane", TPT, Vol. 26, # 5, May 1988, p. 264.

R.D. Edge, "Levitating a Marble," TPT, Vol. 24, # 5, p. 295, (May 1986).

Paul E. Wack, "Measurement of Centripetal Force Using A Rotating Manometer", TPT, Vol. 23, # 5, May 1985, p. 315 - 316.

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Ernest Zebrowski, Jr., "On the Derivation of the Centripetal Acceleration Formula", TPT, Vol. 10, # 9, Dec. 1972, p. 527, reprinted in TPT, Vol. 40, # 9, p. 554, Dec. 2002

"Centripetal-Centrifugal Force Again," TPT, Vol. 3, # 4, April 1965, p. 173.

Peter Ronhovde, Rudy Sirochman, "Center of Mass Correction to an Error-Prone Undergraduate Centripetal Force Experiment", AJP, Vol. 71, # 2, Feb. 2003, p. 185.

Isaac Newton and Richard Conn Henry, "Circular Motion", AJP, Vol. 68, # 7, p. 637, July 2000.

Herbert R. Newhall, "Modified Centripetal Force Apparatus", AJP, Vol. 45, # 5, p. 496, May 1977.

Robert T. Bush, David M. Durham, "Circular Motion and Centripetal Acceleration in Introductory Physics", AJP, Vol. 43, # 1, Jan. 1975, p. 99.

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S. J. Williamson, A. Korda, "A New Twist for a Centripetal Force Experiment", AJP, Vol. 40, # 3, Mar. 1972, p. 482.

M- 370: "Lift Ball in Bottomless Cup," DICK and RAE Physics Demo Notebook.

Neil. A. Downie, "Centripetal Force And Centrifugal Projectiles", Ink Sandwiches, Electric Worms and 37 Other Experiments for Saturday Science, p. 131.

"Innovative Uses", Vernier Software & Technology, The Caliper - Spring 2004

"The Penny in a Balloon," Physics From the Junk Drawer, 3rd Edition, The Science House, North Carolina State University, p. 25.

Mail Questions and Comments to: Dale Stille