We use the word 'energy' a lot in our everyday conversations. There are many different forms of energy we use every day to move, talk, cook, jump, or to turn on light, heat, music, and TV. In this lesson, we will learn about energy and its various forms with the situations you experience in everyday life.
Let's get started.
Energy makes things happen. Every time something moves, it is because of energy. Every time something gets warmer, it is because of energy. Every time something makes a sound, it is because of energy. We use energy to think, play, and talk. In fact, every time we do anything, we use energy!
We use energy to heat and cool our homes, schools, and offices. We use energy for lights and appliances. Energy makes our vehicles move, planes fly, boats sail, and machines run.
All living things need energy too. Plants use the light from the sun to grow. Animals and people eat the plants and use the energy that was stored. Food is fuel for the energy needs of our body.
Have you noticed after an intense game of football (or any sports), how your body feels hot? It is because your body produces heat energy.
In simple terms, energy is the ability to do work. Energy comes in many different forms and we use it in many ways. Let's look at some examples from our daily life:
Which has more energy - a plane flying in the sky or a book falling off a table? The plane flying in the sky has more energy because it is traveling much faster than a book, and also because the plane is heavier than the book.
When hot chocolate cools down, does it gain or lose thermal energy? It loses thermal energy because the milk is releasing its thermal energy (or heat) to the surroundings and is no longer absorbing thermal energy from the rising temperature of the stove.
How do you think coffee machines or TV start working when they are plugged into the socket? This is because electrical energy travels through power lines and then gives energy to lots of different machines to work.
Which sound has more energy - truck's horn or water fountain? The horn has more energy because the louder something is, the more sound energy it has.
The energy possessed by an object is measured in terms of its capacity of doing work. The unit of energy is, therefore, the same as that of work, and that is Joule (J). 1 Joule (J) is the energy required to do 1 joule of work. A joule refers to that amount of energy passed to a body by working to move it for 1m distance against a 1N force. A larger unit of energy called kilojoule (kJ) is used. 1 kJ = 1000 J.
Kinetic energy - Any moving things use kinetic energy. For example, flying an airplane in the sky, throwing balls, running, cycling, etc. are examples of kinetic energy. A moving car on the road is having kinetic energy whereas the parked car is not having kinetic energy. It means kinetic energy only exists when a body or object is moving. When an object is on rest, its kinetic energy becomes zero. This means, when Motion = 0, Kinetic Energy = 0. It ranges from zero to a positive value. Example: A child swinging on a swing. No matter whether the swing is moving forward or backward, the value of the kinetic energy is never negative.
Potential energy – It is the energy of an object’s position. Example: When a child swinging on a swing reaches the top of the arc, she has maximum potential energy. When she is closer to the ground, her potential energy is at its minimum (0). Another example is throwing a ball into the air. At the highest point, the potential energy is the greatest. As the ball rises or falls it has a combination of potential and kinetic energy.
Mechanical energy – This is the energy that results from movement or the location of an object. Mechanical energy is the sum of kinetic energy and potential energy. Examples: An object possessing mechanical energy has both kinetic and potential energy, although the energy of one of the forms may be equal to zero. A moving car has kinetic energy. If you move the car up a mountain, it has kinetic and potential energy. A book sitting on a table has potential energy.
Chemical energy - Chemical energy is the energy that is stored in the bonds of atoms and molecules. When this chemical reaction occurs, this energy is released. We use chemical energy in our car in the form of fuel (petrol/diesel) to drive. Batteries, biomass, oil, natural gas, and coal are examples of stored chemical energy. Food is also a good example of stored chemical energy. This is energy is released during digestion.
Electrical energy - Energy generated by tiny charged particles called electrons. A lightning bolt is one form of electrical energy. Almost all our appliances like laptops, coffee machines, mobile phones, vacuum cleaners, and television work with electricity.
Heat energy – It is also known as thermal energy. The energy that comes from a fire is thermal energy. It reflects the temperature difference between the two systems. As we know the matter is made up of molecules. When we raise the temperature of matter the particles vibrate faster. Heat energy is the energy that comes from the temperature of matter. A cup of hot coffee, electrical or gas stoves, room heater, etc are examples of thermal energy.
Light energy - This is also known as Radiant energy. The Earth gets a lot of its energy from the light of the Sun. Plants take light energy from the sun and convert it into chemical energy (food) which helps them to grow, this is known as photosynthesis.
Sound energy – The louder we scream, the more sound energy we use. Anything that you hear is the sound energy. In addition to our voices, there are many other examples of sound energy: clapping your hands, playing guitar, barking dogs, etc.
Nuclear energy – Nuclear energy is stored in the nucleus of atoms. This energy is released when the nuclei are combined (fusion) or split apart (fission). Example: Nuclear fission, nuclear fusion, and nuclear decay are examples of nuclear energy. Atomic detonation and power from a nuclear plant are specific examples of this type of energy. Nuclear power plants split the nuclei of uranium atoms to produce electricity.
Electromagnetic energy – Electromagnetic energy or radiant energy is energy from light or electromagnetic waves. Example: Any form of light has electromagnetic energy, including parts of the spectrum we can’t see. Radio, gamma, x-rays, microwaves, and ultraviolet light are some examples of electromagnetic energy.
Gravitational energy – Energy associated with gravity involves the attraction between two objects based on their mass. It can serve as a basis for mechanical energy, such as the potential energy of an object placed on a shelf or the kinetic energy of the Moon in orbit around the Earth. Example: Gravitational energy holds the atmosphere to the Earth.
Ionization energy – It is the form of energy that binds electrons to the nucleus of its atom, ion, or molecule. Example: The first ionization energy of an atom is the energy needed to remove one electron completely. The second ionization energy is energy to remove a second electron and is greater than that required to remove the first electron.
The Law of Conservation of Energy states that energy can never be created or destroyed, but it can only be changed from one form to another. One example is the chemical energy in food that is turned into kinetic energy when we move.
Mass is closely related to energy. As a result of the equivalence between mass and energy, any stationary object with mass has got an equivalent energy amount that is referred to as the rest energy. A rest mass refers to the mass of a stationary body. An increment of energy to the body above the rest energy will raise the total mass of the object. Example: heating an object leads to an energy increase that is measurable as a small mass increase.
RENEWABLE ENERGY
Renewable energy is energy produced from sources that do not deplete or can be replenished within a human’s lifetime. The most common examples include wind, solar, geothermal, biomass, and hydropower.
Solar energy refers to the type of energy from the sun. it can be converted into electrical, heat and chemical energies. For example, solar panels are used to tap solar energy and then convert it into electrical energy. This energy can be used for lighting or heating. Solar energy is also applied in electrical appliances like mobile phones. This energy type is very abundant in tropical regions of the world where it has been used traditionally to dry crops like coffee, maize and rice. Some of the advantages of this type of energy are that it is cheap, inexhaustible, it has a wide range of sources and it is a clean energy source.
Wind energy refers to energy from winds. Windmills are used to convert wind energy into mechanical energy that can be used in different ways. These include generating electricity, grinding cereals and pumping water. For centuries, wind energy has been exploited for propelling ocean vessels like dhows and ships. The areas that have open landscapes are the major potential areas with wind energy.
Energy obtained from water is called hydro-power. It is produced when water is in motion. Water flowing at high speed has a lot of kinetic energy which can do work. For example, the force of water can be used to turn the grinding mills for grains. The energy is also used to turn turbines which generate hydro-electricity.
NON-RENEWABLE ENERGY
In contrast, non-renewable energy is the energy that comes from sources that will run out or will not be replenished in our lifetimes. Most sources of non-renewable energy are fossil fuels, such as coal, gas, and oil.
Petroleum refers to the liquid and gaseous hydrocarbons from animal and plant matter that were laid down, compressed, and turned into these forms within the sedimentary rocks. After petroleum is refined, different products are obtained. These products include petrol (gasoline), aviation fuel, lubricants, kerosene, and bitumen. These products are used for different purposes. Industrial diesel is applied in industries in furnaces and boilers, to generate fuel for vehicles, ships, locomotive engines, and machinery.
Coal is a brown or black rock, mainly made up of carbon formed millions of years ago from the compression of plant matter. The use of coal as a source of power has reduced in recent years with the discovery of geothermal power, hydroelectricity, and petroleum.
Natural gas is a type of gas that forms underground and forms on the upper layers of crude oil but may also occur on its own. It is used in industries mainly for heating and domestic purposes for heating, lighting, and cooking.
