Energy Transfers And Particle Motion

Walk out of a warm house on a frosty morning and take hold of the metal gate latch, then rest your other hand on the wooden gatepost beside it. The latch is painful. The post is merely chilly. Both have stood in the same air all night, so a thermometer pressed against either one would give you the same reading to within a fraction of a degree. Your hand is not measuring their temperature at all. It is measuring how quickly each of them is emptying your fingers of energy, and on that measure the two are nowhere near each other.

This lesson is about rate: not how much energy an object holds, but how fast it moves and what governs the speed. You will trace energy through a solid by vibration and by free electrons, watch a fluid carry its own energy upwards because heating has made it thinner, work out why a film of sweat leaves your skin colder than it found it, calculate a surface area to volume ratio, and see why most substances grow a little when they are warmed. It is the best examined topic on the whole physics paper: on the Core Tier specimen it carries a ten mark question, an eight mark question and the paper's only six mark question, and the Extension Tier sets two of those three word for word.