When I was a scout we were taught how to make fire by rubbing two sticks together. The friction occurring between them generates heat energy and if there is enough heat energy the wood at that point may smoulder and eventually catch fire. You have to move then very fast to prevent them cooling down faster than you can inject energy. The technique usually involved making a depression in one piece of wood and giving the other piece of wood a blunt point. The point was put in the depression and rotated, possibly by holding it between your hands and rubbing backwards and forwards.
People
used to add dry grass and wood shavings so that there was more chance of flames, a bigger
surface area and so more chance of oxygen getting to the initial spark.
But what is
friction. Very simply it is the movement of one rough surface against another allowing the
motion energy to be converted to heat energy. If the two surfaces were metal it would be the
breaking off of tiny projections on the surfaces
As to how long it might take – I really
don't know. It probably takes a minute or two if everything is really dry and you use shavings
or grass as I suggested.
I have seen two Aborigines making fire in Australia. It took
less than a couple of minutes for them to light a handful of dried grass that they then used to
start a fire in a pile of twigs.