Relationship Between Quantity of Heat and Temperature

The quantity of heat cenergy and the temperature of a burning match stick are compared with that of the boiled water in a container.

The temperature in a large container is less than that of a burning match stick, but the total quantity of heat energy in the boiling water is greater, because there are more molecules in the boiling water than in the match stick. The number of molecules in the match stick in less but they have greater kinetic energy. So the temperature of the match stick is high. The number os molecules in water is large although the KE of each is smaller so it has a large quantity of heat energy.

Temerature is the measure of the averaage kinetic energy of the molecules. But the same amount of heat energy generally affects different substances differently (specific heat capacity).

Unit Of Heat Energy

Heat energy, like other forms of energy is measure in joules(j). Heat enrgy is also measured in calories.

1 calorie =  4.2 J

1 joule is a small quantity of heat. The heat energy produced by a burning mutch stick is about 2000J.

The larger unit of heat are kilojoule (KJ) and megajoules(MJ)

1000J = 1 KJ

1000 KJ = 1 MJ

In order to maintain 37⁰C in our body we need 10 MJ per day. All the energy which we need is derived from food.