This year we are once again  inviting each physics team to create their own “Vacuum Cannon”, which will compete in the Division 3 Activity.  Below you will find a schematic for its construction (though you may modify the design if you so choose).  We will provide a 5 ½ HP vacuum and the golf balls. Prizes will be awarded for “Longest Drive”, “Closest to Target”, and “Best in Show” (yes, the last one is a beauty contest.)  You must use 1 ½  “ pipe for this with a 1 ½ “ PVC “Y” or “T” where the “Y” or “T” is a 2 ½ inch coupling.  Your students may construct their cannon at the length that they desire and may construct their counter-mass however they would like.  A good place to start with the countermass is a piece of wood dowel.  The countermass will be used to propel a golf ball out the end of the cannon (the round gray object in the T in the figure below).  You will find some pictures of vacuum cannons that we have built below.