Whether the matter is in the form of solid, liquid or gas, it consists of molecules. These molecules are in constant movement bombarding each other like billiard balls. Such characteristic of motion is responsible for the production of heat. However, the amount of heat produce depends on the speed of collision produced by the molecules. The faster the motions of the particles are the higher the thermal energy is enough to change the state of the matter from solid to liquid or to gas. With this, it is inevitable not to relate heat with the kinetic theory of matter.
Heat is defined as the transfer of energy from an object with higher temperature to an object with lower temperature (Freeman, 2005). For instance, if you touch a hot iron, you feel the heat as the thermal energy enters your hand because the iron is warmer than your hand. Consequently, if you touch a cold drink, the energy passes out of your hands and into the cold drink. The heat which passes from the hot iron to a colder hand originates in the internal energy of the hot object. The internal energy is the sum of the kinetic energy of the molecules called the molecular energy. The kinetic energy is called the thermal energy. Both kinetic and potential energies of the molecules provide the ultimate source of heat which is only appreciated when there is a difference in the temperature of objects coming in contact together until equilibrium is reached. With this, it is important to note that when one is exposed outside the cold winter, there is a need to wear a coat to slow down the flow of the heat from the body.
Temperature is the state of coldness and hotness of an object measured with a device called thermometer. The expansion and contraction of the mercury within the thermometer is compared in a scale to measure how much thermal energy is present in certain molecules of an object.