What is Energy?
Energy is the basic essence of the Physical Universe. Energy is what the Universe is made of.
There are many different forms of energy.
Energy either exists in a stored form - or is it is in the process of being transformed from one form to another - or it is being transferred from one point in space to another.
When energy is transferred (or moves) it is called Heat. Heat is energy in motion.
The different types or forms of energy can be grouped into three broad categories: Kinetic Energy, Potential Energy and Heat.
Energy is something that has the ability to make things happen. It is defined as the ability or capacity to do work.
Energy cannot be created or destroyed. Nothing happens without the involvement of
energy and everything that happens involves a change in energy from one form to
another.
Different Forms of Energy
We can experience some forms of energy when they are released (or transformed).
We see things when our eyes intercept light – or radiant energy. If we
sit on the beach on a clear day, we can feel the warmth of the sun. If we touch
something that is too hot, we feel pain as the energy is transferred to our
fingers.
Forces are often created when energy is released.
We can feel the forces that are created when energy is used to accelerate a car or an airplane
or a roller-coaster.
Stored Energy
We cannot usually sense the presence of stored energy – unless we make the mistake of triggering its release. Chemical Potential Energy is stored in chemicals – such as in gunpowder or inside batteries.A form of Potential Energy called Kinetic Energy is stored in anything that is moving – such as a bullet or a car.
Energy can also be stored in an object by adjusting its position when it is under the influence of a force field. If we use a crane to lift a heavy object, the higher we lift it, the more Gravitational Potential Energy it contains.
Work
Energy is released or transformed whenever anything happens. Work is done whenever energy is transformed or released.Everything that happens involves energy. Energy creates forces and forces do the work. Energy is released when we burn fuels or use electricity. If we run an engine, boil some water or bask in the sun, we use energy. It takes energy for plants and animals to grow. It takes energy for something to change its temperature and it takes energy for something to change its speed. When we say that energy is released, it is actually being transformed from one form to another. When work is done on an object or system, it gains energy - or the energy it contains becomes more useful. When an object or system does work, it transfers energy to another object or system.
Energy cannot be created or destroyed
When energy is used or released, it is transformed from a more useful form to a less useful form.Energy, Time and Triggers
Everything that happens in the universe takes time. Every occurrence also needs to be triggered.When an energy change is triggered, it requires an input of energy (usually a relatively small amount) from a source outside of the system in which the energy change is about to occur. Once the energy change has been initiated, it will continue (and take time to do so) until the object or system involved reaches a more stable state with a less-useful amount of energy.
For example: When the fuse in a firecracker ignites the gunpowder in the cracker, this triggers the rapid release of chemical potential energy that is stored in the gunpowder. When the gunpowder burns, it creates a relatively large amount of gas and also heats the gas so that it is under a very large pressure. This pressure (force) causes the cracker to burst, sending out a loud shock wave. Even though the explosion of the cracker seems instantaneous, it does take a certain amount of time. This amount of time might be quite small but nothing happens instantaneously. The release of energy in the firecracker continues until the chemical potential energy of the remaining material (the products of the reaction) drops to a lower and more stable level.
Heat - or Energy in Motion
Energy can move from one point or region in space to another.Heat is defined as energy in motion.
Kinetic Energy
Kinetic Energy can be contained or stored in something that has motion. The more speed and object has, the more energy it contains. If you are hit on the arm by a small lead ball that is thrown at you, the pain or damage caused will be relatively small. If, on the other hand, you are hit by the same lead ball that is fired from a gun, the pain and damage will be substantial.The faster moving object has much more energy and this is transferred to your arm on impact. The amount of energy that a moving object contains is equivalent to half of its mass multiplied by the square of its velocity.
KE = ½*M*V*V
Where KE is the kinetic energy in Joules
M is the mass in kilograms and
V is the velocity in meters per second
Potential Energy
Potential Energy is determined by the position of an object in a force field. As we mentioned before, we are surrounded by force fields and these affect us and everything around us by enabling objects to contain potential energy. The most familiar form of potential energy is Gravitational Potential Energy. This is the energy that an object has as a result of its position in a gravitational field. We learn very early in life that jumps can cause lumps. The further we fall, the more it hurts. If we carry an object to the top of a ladder, we increase its gravitational potential energy. (We also increase our own gravitational potential energy.) If we then drop the object, it starts to accelerate towards the ground under the force of gravity. While it does so, its potential energy decreases as its distance from the ground decreases and its kinetic energy increases as it gathers speed.<
