Explain why wax melts at different rates along a metal rod heated at one end, and why it wouldn't melt along a wooden stick.

a) The wax at position A melts first. This is because position A is closest to the heat source (the candle). Heat travels along the metal rod, and the wax closest to the source will receive enough heat to melt before the wax further away.

b) The heat reaches the wax on the metal rod by the process of conduction.

c) When one end of the wooden stick is heated, the wax at positions A, B, C, and D will not melt, or will melt very slowly. Wood is a poor conductor of heat (an insulator), so heat does not transfer efficiently along the stick to reach the wax.