When a person uses an iron to remove the wrinkles from a shirt, why does heat travel from the iron to the shirt?

In physics, there is a rule that the heat always travels from the hotter object to the cooler object. In this case, as the iron is hotter than the shirt, the heat will travel from the iron to the shirt.

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.