What is Energy?

Hello Kids! I am ready to start this section dedicated to you!! As I already told you, in this section I am going to talk about energy, energy savings and eco-friendly behaviours. Moreover, I’ll post some funny games, curiosities and experiments you can do with your friends, teachers or parents to discover more about this interesting topic. I hope you will enjoy following this blog!!!

I bet that some of you are asking yourselves “Why should I care about energy savings?”, “Why more and more people are talking about the necessity of reducing energy consumption?”, “Why should I do my part, when my contribute is just a drop in the sea??”. But, above all, I bet that most of you are thinking: “What is this Energy we should save??”, “How can I do my part?”

So, first of all, let’s discover What Energy is.

Energy is something that can’t be directly seen with the naked eye. On the contrary, it’s possible to understand that energy is present because of its capacity of producing an effect (“work” or “heat”). For this reason, energy is also defined as an “indirectly observed quantity”. This means that it’s possible to observe or measure energy only by observing or measuring the work (or the heat) it produces. For example, you can understand the presence of electricity only when it produces some useful work to keep your ice-cream cool in the fridge or to bake your grandma’s pie in the oven. In the same way, you can experience the presence of energy when the wind starts to turn your colourful windmill.

A characteristic of energy is that there are several types of it. Among others:
potential energy, the energy stored in an object because of its position. If you move an object around, the higher the object’s position above the earth’s surface, the higher its potential energy.
Elastic energy, the energy stored in an elastic object (like a spring) because of its deformation (e.g. stretch or shortening).
Kinetic energy, the energy associated with the speed of an object: the higher the speed, the more the kinetic energy.
Electric energy (or electricity), the energy generated by the flow of electric charges (like protons and electrons) inside a conductor. A conductor is a material (like copper, iron, salted water) that allows the electricity flowing through it. On the contrary, materials like rubber, plastic, or ceramic are called non-conductors because they oppose to the flow of electric charges.
Thermal energy (or heat), the energy generated by the chaotic motion of the internal particles (atoms) of an object: the hotter the object, the faster the atoms vibrate. Thermal energy is transferred from a hotter object to a colder one because the rapidly vibrating molecules in the hotter object yield some energy to the slowly vibrating molecules in the colder one.

Another important characteristic of energy is that it can be transformed from one form to another one. The elastic energy stored in a loaded catapult is transformed into kinetic energy once you let the rubber strips go. When you rub your hands to warm them up, the mechanical work you do is transformed into heat. The figure below shows another interesting example of energy transformation. The water contained in the dig stores a certain amount of potential energy because of its position up on the mountains. When the control gate opens, the water starts to flow down inside the pipe. Since the water is moving from a higher position to a lower one, it loses some potential energy: the potential energy lost is transformed into kinetic energy. Once the water reaches the turbine, part of its velocity is used to move the turbine: an alternator transforms the kinetic energy contained in the water into electricity. Then, power lines bring the generated electricity to our homes to power bulbs or electric heaters during winter. When we switch on our electric heaters, the electric energy provided is transformed into heat to warm up the room.


(Image created and animated by Virginia Gori)

Now that you learned what energy is, I bet you are asking yourselves “Why should I care about saving it?”, “What is the “renewable energy” that more and more people all around the world speak about?”, “Why is so important to use “renewable energy” rather than “conventional” one?”. I will explain you all these things in the next post!!! See you soon!


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