* Snow: Snow has a slightly higher coefficient of friction than ice, but it is still considered to be a very slippery surface. This is because snow is made up of tiny ice crystals that are not very well bonded together.
* Wax: Wax is another substance that has a low coefficient of friction. This is why wax is often used to lubricate surfaces that need to move smoothly, such as the tracks of a roller coaster.
* Graphite: Graphite is a form of carbon that has a very smooth surface. This is why graphite is often used to make pencils and lubricants.
* Teflon: Teflon is a synthetic material that has a very low coefficient of friction. This is why Teflon is often used to make non-stick cookware and other surfaces that need to be resistant to wear and tear.
