Purpose: To demonstrate the force atmosphereic pressure can apply to objects.

10 foot long 1.5 inch schedule 40 PVC pipe with a vacuum attachment, two small sheets from a metallic balloon, and two PVC 1.5 inch connectors.

To use the cannon safely:

1. Lay the cannon on two tables supporting its entire length, being sure to aim away from anyone.
2. If launching at the backdrop cloth, keep the cannon a minimum of 7 feet away.
3. Ensure that no one can enter the line of fire (anywhere in front, or in case of failure, anywhere behind the cannon's two openings) by locking or putting notices on the doors
4. Place the ping pong ball in the end closest to the vacuum adapter. (The ball cannot get in the way of the vacuum so do not worry if it rolls some)
5. Place unused metallic sheets over each end, using the PVC connecter pieces to hold it in place.
6. Connect the vacuum and begin evacuating the tube
   ** DO NOT ALLOW ANYONE IN FRONT OF, OR BEHIND THE CANNON**
7. After allowing the tube to be evacuated for 3 minutes, ask everyone to cover their ears,and then puncture the metallic strip on the vacuum side with scissors, or a long sharp knife.

To make the demo more quantitative, two photogate timers and an interface can be set up to measure the muzzle velocity of the ping pong ball.

It has not been tested yet, but the cannon should be able to shoot the ping pong ball through various targets. These targets should be placed in the wire cage to stop shrapnel. Suggested targets are:

• 3 soda cans in a row (placed upside down so as to hit the thin parts). The ball should penetrate two of the three cans.
• A thin piece of plywood or a notebook

Notes on Safety:

• For an idea of how the demo behaves, watch this video.
• Before Starting the demo, warnings should be placed on the doors leading into the classroom to make sure no students enter for the entirety of the firing process.
• It is possible for the cannon to misfire at any point while it is being evacuated. The ball can be shot out of either end of the cannon. The only safe places to stand are to the side of the cannon; ensure that no one (including the person firing the cannon) is in front of or behind the cannon.
• When puncturing the metallic strip, hit it firmly and quickly to avoid a misfire happening while your hand is in the way.
• This demo is LOUD. It is recommended that all students cover their ears during the entire evacuation process and that the person firing the cannon wear protective ear coverings.
• If you are planning on launching the ball at an object, arrange them in the cage in front of the cannon BEFORE evacuating it.

References:
Stokes pingpong cannon video
BYU's Ping Pong Cannon page
The Ping Pong Cannon: A Closer Look