When the Magnet Linear Accelerator shoots, it will happen too fast to see. The ball on the right will shoot away from the gun, and hit the target with considerable force. Our one foot long version is designed so the speed is not enough to hurt someone, and you can use your hand or foot as a target.
How does it work?
When you release the first ball, it is attracted to the first magnet. It hits the magnet with a respectable amount of force, and a kinetic energy.
The kinetic energy of the ball is transferred to the magnet, and then to the ball that is touching it on the right, and then to the ball that is touching that one. This transfer of kinetic energy is familiar to billiards players — when the cue ball hits another ball, the cue ball stops and the other ball speeds off.
The third ball is now moving with kinetic energy. But it is moving towards the second magnet. It picks up speed as the second magnet pulls it closer. When it hits the second magnet, it is moving nearly twice as fast as the first ball.
As we add more magnets, the speed goes up by a smaller amount each time. But the distance the ball will roll, and the damage it causes to what it hits, is a function of the kinetic energy, and thus a function of how many magnets we use.
We can keep scaling up until the kinetic energy gets so high that the last magnet is shattered by the impact. After that, adding more magnets will not do much good.