Vacuum Cannon

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 Code Number :   2B30.70 

Disclaimer:

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.

Condition :   Excellent
Principle :   Air pressure, Vacuum
Area of Study :  Fluid Mechanics   
Equipment :   Vacuum Cannon, Vacuum Pump, 40mm Ping-Pong balls, 3-M packing tape that is 3 inches wide, pop can holder with empty pop cans.

Procedure :   We have three different length vacuum cannons.  They are 5 feet, 7.5 feet, and 10 feet in length.  Choose the one that best fits your classroom. 

Place the vacuum cannon on the table and clamp the pop can holder directly in front of the cannon muzzle.  Place a 40mm Ping-Pong ball into the muzzle and roll it all the way down to the stop provided by the vacuum inlet.  Place 3-M packing tape onto each end of the cannon taking care to insure that the tape is flat so that it doesn't have any air leaks.  Fold an appreciable amount of tape over the ends of the cannon.  This will ensure that premature failure of the vacuum seal does not take place when pumping down the cannon.  Pump the air out of the cannon with the vacuum pump.  This process may be monitored using the attached vacuum gauge on the cannon.  When the desired vacuum is reached, shut the valve on the cannon and turn off the vacuum pump.  Using a sharp object, puncture the tape at the rear end of the cannon ( the end closest to the vacuum connection, gauge, and valve ).  Warning:  When the tape is punctured a very large noise is produced.  The Ping-Pong ball will be driven out the other end of the cannon by the inrushing air and will puncture several soda cans.    These can then be taken out of the holder and passed around to the class.  Warning:  The Ping-Pong ball can theoretically achieve muzzle velocities of 287 m/s.

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   References

Mark Denny, "Internal Ballistics of an Air Gun", TPT, Vol. 49, # 2, Feb. 2011, p. 81.

Yasuo Ogawara, "Plastic Syringe Vacuum Cannon", TPT, Vol. 47, # 4, April 2009, p. 252.

Brett Taylor, "Recoil Experiments Using a Compressed Air Cannon", TPT, Vol. 44, # 9, Dec. 2006, p. 582.

John Cockman, "Improved Vacuum Bazooka", TPT, Vol. 41, April  2003, p. 246-247.

R. W. Peterson, B. N. Pulford, K. R. Stein,  "The Ping-Pong Cannon: A Closer Look",  TPT, Vol. 43, January 2005, p. 22-25.

 

G. Olson, R. Peterson, B. Pulford, M. Seaberg, K. Stein, C. Stetler, R. Weber, "The Role of Shock Waves in Expansion Tube Accelerators", AJP, Vol. 74, # 12, Dec. 2006, p. 1071.

Eric Ayers and Louis Buchholtz, "Analysis of the Vacuum Cannon", AJP, Vol. 72, # 7, July 2004, p. 961-963.

 

Richard E. Berg, "Demo Hints: Vacuum 'Bazooka' ", PIRA, Vol. 3, # 6, 28 Oct. 1988, p. 4.

 

Neil A. Downie, "Vacuum Railroad", pp. 100-107.

 



Mail questions or comments about this site to:  Dale Stille

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