What is energy?
Look around you. Is anything moving?
Can you hear, see or feel anything? Sure... this is because something is making something happen, and most probably, there is some power at work. This power or ability to make things happen is what we can call energy. It makes things happen. It makes change possible.
Look at the sketch below to see an example of things working, moving, or happening... with energy.
Energy move cars along the roads and make aeroplanes fly. It plays our music on the radio and lights our homes. Energy is needed for our bodies, together with plants to grow and move about.
Scientists define ENERGY as the ability to do work.
Energy can be neither created nor destroyed.
KINDS OF ENERGY
With the above explanation in mind, let us learn more.Energy can be (is) stored or transferred from place to place, or object to object in different ways. There are various kinds of energy.
Let's start by looking at KINETIC ENERGY
All moving things have kinetic energy. It is energy possessed by an object due to its' motion or movement. These include very large things, like planets, and very small ones, like atoms. The heavier a thing is, and the faster it moves, the more kinetic energy it has.
Now let's see this illustration below.
There is a small and large ball resting on a table.
Let us say both balls will fall into the bucket of water.
Let's see what is going to happen.
You will notice that the smaller ball makes a little splash as it falls into the bucket. The heavier ball makes a very big splash. Why?
Note the following:
1. Both balls had potential energy as they rested on the table.
2. By resting up on a high table, they also had gravitational energy.
3. By moving and falling off the table (movement), potential and gravitational energy changed to Kinetic Energy. Can you guess which of the balls had more kinetic energy? (The big and heavier ball)
Let's see another classic example.
If you are in a hot room and you turn on the fan, what do you begin to feel? Air (wind). The speedy movement of the fan's blades has kinetic energy, which is then transferred into air (wind) that you now feel.
Other examples of Kinetic Energy include a moving car, moving wheel, and a moving arrow.
Click to see a video example of kinetic energy in use.
SOUND ENERGY
Sound is the movement of energy through substances in longitudinal (compression/rarefaction) waves.
Sound is produced when a force causes an object or substance to vibrate — the energy is transferred through the substance in a wave. Typically, the energy in sound is far less than other forms of energy.
Let's see this illustration.
A vibrating drum in a disco transfers energy to the room as sound. Kinetic energy from the moving air molecules transfers the sound energy to the dancers eardrums. Notice that Kinetic (movement) energy in the sticks is being transferred into sound energy.
Sound vibrations create sound waves which move through mediums such as
air and water before reaching our ears.
Click the icon below to read more on how energy is
measured and how a sound wave is represented.
HEAT-THERMAL ENERGY
Thermal energy is what we call energy that comes from heat. For example, a cup of hot tea has thermal energy in the form of kinetic energy from its' particles. When you pour some milk into your tea, some of this energy is transferred to the particles in cold milk. What happens next? The cup of tea is cooler because it lost thermal energy to the milk.
We cannot discuss Thermal Energy without touching on Temperature.
Temperature
The temperature of an object is to do with how hot or cold it is, measured in degrees Celsius (°C). Temperature can also be measured in in a Fahrenheit scale, named after the German physicist called Daniel Gabriel Fahrenheit (1686 – 1736). It is denoted by the symbol 'F'. In Fahrenheit scale, water freezes at 32 °F, and boils at 212 °F.
A thermometer is used to measure the temperature of an object.
Let's look at two examples to see the difference between heat and temperature.
A
swimming pool at 30°C is at a lower temperature than a cup of tea at
80°C. But the swimming pool contains more water, so it stores more
thermal energy than the cup of tea.
To
boil water we must increase its' temperature to 100°C. It takes longer
to boil a large beaker of water than a small beaker because the large
beaker contains more water and needs more thermal energy to reach
100°C.
Let's look at two examples to see the difference between heat and temperature.
A
swimming pool at 30°C is at a lower temperature than a cup of tea at
80°C. But the swimming pool contains more water, so it stores more
thermal energy than the cup of tea.To
boil water we must increase its' temperature to 100°C. It takes longer
to boil a large beaker of water than a small beaker because the large
beaker contains more water and needs more thermal energy to reach
100°C.
CHEMICAL ENERGY
Chemical Energy is energy stored in the bonds of chemical compounds (atoms and molecules). It is released in a chemical reaction, often producing heat as a by product (exothermic reaction). Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Usually, once chemical energy is released from a substance, that substance is transformed into an entirely new substance.
For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.
Let's see one good example in the fire-place illustration below.
The
dry wood is a store of chemical energy. As it burns in the fireplace,
chemical energy is released and converted to thermal energy (heat) and
light energy. Notice that the wood now turns into ashes (a new substance)
Food is also a good example of stored chemical energy. This energy is released during digestion. Molecules in our food are broken down into smaller pieces. As the bonds between these atoms loosen or break, a chemical reaction will occur, and new compounds are created. When the bonds break or loosen, oxidation occurs almost instantly.
In the example above, notice that new compounds are formed from the breakdown of other molecules or atoms. Chemical reaction causes that.
A chemical reaction is involved in this breakdown. The energy produced keeps us warm, maintain and repair bodies, and makes us able to move about. Different foods store different amounts of energy.
Energy in food is measured in kilocalories (or Calories). Can you think of some very good examples of chemical energy?
Click to see Video example of chemical energy.
Chemical Energy is energy stored in the bonds of chemical compounds (atoms and molecules). It is released in a chemical reaction, often producing heat as a by product (exothermic reaction). Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Usually, once chemical energy is released from a substance, that substance is transformed into an entirely new substance.
For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.
Let's see one good example in the fire-place illustration below.
The
dry wood is a store of chemical energy. As it burns in the fireplace,
chemical energy is released and converted to thermal energy (heat) and
light energy. Notice that the wood now turns into ashes (a new substance)Food is also a good example of stored chemical energy. This energy is released during digestion. Molecules in our food are broken down into smaller pieces. As the bonds between these atoms loosen or break, a chemical reaction will occur, and new compounds are created. When the bonds break or loosen, oxidation occurs almost instantly.
In the example above, notice that new compounds are formed from the breakdown of other molecules or atoms. Chemical reaction causes that.
A chemical reaction is involved in this breakdown. The energy produced keeps us warm, maintain and repair bodies, and makes us able to move about. Different foods store different amounts of energy.
Energy in food is measured in kilocalories (or Calories). Can you think of some very good examples of chemical energy?
Click to see Video example of chemical energy.
ELECTRICAL ENERGY
A battery transfers stored chemical energy as charged particles called electrons, typically moving through a wire. For example, electrical energy is transferred to the surroundings by the lamp as light energy and thermal (heat) energy.
Lightning is one good example of electrical energy in nature, so powerful that it is not confined to a wire. Thunderclouds build up large amounts of electrical energy. This is called static electricity. They are released during lightning when the clouds strike against each other.
Click to see a video example of electrical energy in use.
