The teacher introduces a brief explanation on the context about the importance of energy and the different kinds of energy we can find. We recommend the teacher to check the following link to complement the topic: http://fisica.unav.es/~dmaza/fisica1/mec4.html What do you consider necessary for people surrounding us and for ourselves to move?
Human beings need energy to live, move, breath, keep our heart beating, maintain blood circulating, and even think. The energy the sun provides to the earth is crucial for food production. Foods are our source of energy, so that we can carry out all vital and daily life activities. The food we eat contains stored chemical energy, which transforms in kinetic chemical energy when our bodies move, and at the same time, turns into heat. In addition, human beings require energy for the operation of machines: cars, electric plants, electrical goods, industrial plants etc. To meet those needs, human beings have used as a source: oil, coal, natural gas, which are non-renewable sources. At the same time, human beings use the water of a waterfall (hydraulic energy), the wind (wind power), sunlight (solar energy) etc. those originate from natural phenomena, so they are renewable sources of energy.