 In this video we'll look at how heat and temperature are related, and it's via a property that all materials have called heat capacity. Roughly, heat capacity is the amount of heat required to raise the temperature of a substance. It might seem like that should be the same for everything, but it's not. Say you take one kilogram of water and one kilogram of concrete, both at 25 degrees C, and say you want to raise the temperature of both of them by some defined amount. It would take almost five times as much energy to do that to the water as it would to the concrete. We call this heat absorbing property heat capacity. For something that has a low heat capacity, gaining just a little heat will raise its temperature significantly, whereas something with a high heat capacity like water can absorb a lot of heat energy before its temperature rises very much. For instance, here's a little simulation. It shows a sample of earth and a sample of water with the same mass, both absorbing the same amount of energy from heat lamps. Notice that the temperature of the water rises more slowly. This is because it has a higher heat capacity and so it takes a lot more heat energy to make its temperature rise. Note too, it's the same for cooling. When the lamps turn off, both samples begin to lose heat to the surroundings. The earth with a low heat capacity drops its temperature much faster because a small loss of energy makes a big difference to it, whereas water with a high heat capacity takes a long time to cool down because it has to lose a lot of energy to do so.