Sliding friction is useful for starting fires.
a. If you press a wooden peg against another piece of wood and spin the peg rapidly, it can become hot enough to ignite. The peg produces thermal energy no matter how fast it spins, so why is it important that it spin rapidly?
b. If you strike a piece of flint against a piece of steel, you can shave a red-hot spark off the steel. However, moments later the surface of the steel itself barely feels warm. What happens to the thermal energy in that surface?
c. When you rub a match on a matchbook, it suddenly bursts into flames. The principal source of heat here is a chemical reaction in the match head. What purpose does the initial thermal energy serve in starting this reaction?
d. what is a safety match? How does it work?
e. You might see a "cowboy match" in a movie light a match by rubbing it on the heel of their boot. How does a match light that way?