neodymium magnet sphere and magnet cubes 5*5 mm ramp
The device is made of a rail fitted with magnets. The rail could be in aluminium and the magnets are fixed below. The most important point is the positioning of the magnets. They must present the same magnetic pole on one side, for the entire row. For example, all magnets on the left side must present the south pole and all magnets on the right side the north pole. In the experiment shown in the video, small cubic magnets have been used but it is also possible with cylindrical magnets. If the two poles are on each face, the magnets have to be placed vertically, as if they were wheels. The space between the magnets is not so critical, but in order to get a good acceleration they must be close enough of each other. It depends of the strength of the magnets, for our experiment they were placed approximately each 5 mm (1/5”).
Then at the end of the rail, two magnets are used instead of one. This is to stop the sphere magnet motion with a stronger magnetic field.
The magnetic sphere is placed approximately 2 cm (1”) from the beginning of the ramp (the opposite side of the two magnets). There is no need to set the sphere in rotation, the magnetic field of the ramp's magnets will attract it towards the end of the ramp. Then the two magnet's stronger field will stop the motion. Each magnets set gives the same speed increase, the speed increase comes from the addition of this speed to the remaining speed from the previous magnets set, thanks to inertia.
The glass sphere (marble) is placed just before the ending magnets of the rail, so that the magnet sphere hits it with its maximum speed. While the magnet sphere is stopped by the magnetic trap, the marble is ejected from the launcher.