# Heat energy as a form of energy

Heat energy is a form of energy that makes us feel hot. Heat energy can also be defined as a form of energy which flows due to temperature difference. It is produced by sun, friction or fire. Heat can also be produced during chemical reactions

Use of heat energy: it  can be used for the following things: cooking, drying our cloths, in industrial heat is used in production of goods.  Engine like motor engine or our generators in the house use heat from burning fuel to operate and many more uses of heat.

Concept of temperature: temperature is defined as the measure of degree of hotness coldness of a body.Temperature can be measured using Thermometer. Every thermometer makes use of thermometric substance which changes in volume due to change in temperature.

## Effect of heat energy on matter.

It is has been observed and established that when heat is applied on a body, various changes take place, which include the followings:

1. Chemical change
2. Change in physical properties
3. Change in the temperature of the body
4. Change in the state of the body, like from solid to liquid and vice versa
5. Change in the pressure of the body
6. Thermionic emission occurs, that is emission of electron from metallic surface

### Kinetic theory of matter: The kinetics theory of matter states that:

• All matters are made up of atoms and molecules
• The molecules of matter are in constant state of motion
• The molecules of matter posses kinetics energy due to its constant motion
• The molecules exert attractive force on one and another
• The nearer the particles are to each other the greater the attractive force

#### Using kinetic theory to explain the temperature of a body

It is established fact that as the temperature of a body or molecule increase, then the kinetics energy increase and vice versa. For example , from the statements of kinetics theory of matter, molecules poses kinetics energy of motion, so if heat is applied to this moving molecules , their velocity increase and this result in increase in their average kinetics energy (1/2mv2 ), which lead to increase in temperature.

On the other hand, if heat is reduced, the velocities of the molecules decrease and the average kinetics energy decrease also, which eventually lead to decrease in temperature.

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