Fred and Bob are racing cylindrical magnets down tubes of various materials. All of the magnets weigh the same and have the same dimensions. All of the tubes are the same length and have an inner diameter just larger than the outer diameter of the magnets. There is negligible friction when the magnets travel through the tubes.
Since they don't want the magnets to get stuck, Fred and Bob are using non-ferrous materials that magnets won't stick to. They have one tube for each material: wood, glass, aluminum, and plastic. Each of the tubes is set up at the same angle with respect to the floor and they are all in the same room on Earth.
Assuming they have a perfect method of timing each run, which tube has the longest time? |