Gauss Cannon

We have made a Gauss cannon, to demonstrate the phenomenon of a collision seemingly creating energy by means of a permanent magnet. It seems like it is created, because the ball that rolls away form the magnet at the end can reach a higher point that the incoming ball was dropped from.

This increase in energy actually happens because of the potential energy of the magnet and the balls around it is lower when the incoming ball replaces the ball that rolls away. This decrease is due to the distance of the balls relative to the magnet.

• 3 magnetizable steel balls, diameter 20 mm
• 1 permanent neodymium cilinder magnet, diameter 20 mm, length 9 mm

WARNING: Neodymium magnets are quite brittle, so handle with care!

• 1 compression spring, diameter 9.5 mm, length 16 mm
• 1 plate of transparent plexiglass, 3 mm thick, at least 300x120 mm surface
• 1 plate of plywood, 3 mm thick, at least 600x300 mm surface
• Sponge, 5 mm thick, 65x30 mm surface
• A small amount of iron filings
• Wax
• Wood glue
• Sandpaper
• Acrylic glue

First, lasercut all of the necessary parts using the files supplied below. Make sure the red lines are cut and the black lines are engraved. The names of the files indicate which material they should be cut out of.

The starting mechanism is constructed by sliding the two parts of the spring holder into each other, as seen in the first image. This part is then attached to the track, and the spring is put around it, as seen in the second image. The button is constructed as seen in the third and fourth image. The stopper is then constructed as seen in the fifth image, after which it and the support parts are inserted into the track.

The stopper and the button parts need to be sanded and waxed for optimal results.

Connect the two track parts to each other, while making sure the button parts press on the spring, and the support parts go into their respective holes, as seen in the first image. Then, while holding the two parts together, insert the large support parts as seen in the second and third image.

Now, construct the catch box as seen in the first image. Glue sponge to the bottom and the back of this box. Glue all the sides to the back and each other, except for one of the sides, otherwise getting the ball out will be quite difficult. Connect the box to the track as seen in the second image.

Set the track on the bottom plate as seen in the first image, and place the track support parts over the track.

Place the 5 parts shown in the first image behind each other, and connect them as seen in the second image, so the magnet is between the leftmost and rightmost parts.

Place the part in the first image between the track parts in the middle of the track, as seen in the second image. Place the magnet holder on the track, making sure everything fits nicely, as seen in the third image.

In the first picture above, the components for the box made of plexiglass are shown. All parts are modular, meaning that they can be disassembled anytime. Shove all the parts into each other as shown in the picture and glue the bottom and side edges of the box so no iron filings can fall through. At last, put some iron filings in the box to visualize the magnetic field and set the box over the magnet on the track. The layer of iron filings should be quite thin, and the iron filings should be spread out across the bottom of the box for optimal results.

Place two balls to the right of the magnet, and one to the left of the stopper, as seen in the first image.