A matchstick can light a tiny splinter of wood but not a big log of wood.A splinter of wood has a
low ignition temperature.A burning matchstick can produce sufficient heat to reach the ignition
temperature of the splinter of wood therefore a matchstick can light a splinter of wood directly.
The ignition temperature of log of wood is high and cannot be reached by the small heat produced by
a burning matchstick.So,a matchstick cannot light a log of wood directly.In order to burn a log of
wood,a small fire is first started by burning straw with a matchstick,and then the log of wood is placed
over this fire.Heat of this fire then heats the log of wood to its ignition temperature due to which the
log of wood starts burning.