What is energy?
Something has energy if it has the ability to do work.
Work shifts energy from one system to another.
Energy cannot be made or destroyed. It can only be changed (transforms) from one type to another. There are different types of energy which I will cover in the next few pages.
Thermal energy is an energy caused by the movement of particles in the objects. This produces heat. Therefore, the more movement there is, the more heat it will create. This means that whenever there is more heat, there is more thermal energy.
Thermal energy is a type of kinetic energy (6th card).
Adding ice to a glass of water causes the temperature of the water to decrease because the thermal energy in the water causes the ice to melt.
Electrical energy is energy that comes from electrical potential energy.
Some objects carry elctrical charges and create electric fieds. These charged objects can exert forces on each other. You get an electrical current when charged particles move through a wire.
Once electrical energy leaves its source, it is instntly transformed into a different type of energy.
In a car battery, the chemical reaction creates an electron which has the energy to move in an electric current. These moving charges provide electrical energy to the circuits in the car.
Nuclear energy is a stored energy which is stored in the nuclei of atoms.
It is released in the form of radioactive radiation.
The fusion reaction in the sun provides our planet with all of the energy it needs for living organisms to survive.
Strain energy is energy stored by a system undergoing deformation.
It's released when atoms in a molecules are rearranged in a chemical reaction.
Balancing chemical formulae
Kinetic energy is one of the two main types of energy.
Moving things have kinetic energy. The more mass a thing has and the faster it moves, the more kinetic energy it has. All moving things have kinetic energy, even very large things like planets, and very small ones like atoms.
Kinetic energy includes many forms of movements such as vibrations and rotations.
An aeroplane has a large amount of kinetic energy in flight due to its large mass and fast velocity.
It is a type of potential energy.
Chemical energy is stored within the bonds of the atoms and molecules that make up a substance. Once chemical energy is released from a substance, the substance is transformed into a new substance.
When propane gas is burned for cooking on a grill, the chemical energy stored in the bonds of propane molecules are broken and heat is released for cooking.
All objects have internal energy. This includes: energy caused by the movement of particles in the object, sometimes called thermal energy due to the bonds between particles, sometimes called chemical energy.
It is a stored type of energy.
A glass of water at room temperature which is kept on a shelf or table. When we analyse it under a microscope we can see all of the molecules moving fast.
Gravitational Potential Energy
Gravitational energy is a stored energy and is closely linked with kinetic energy.
When an object is moved higher, it gains gravitational potential energy. The amount of energy it gains depends upon; the mass of an object, the extra height it gains and the gravitational field strength. In other words, how great gravity would act on it.
A rock sitting at the edge of a cliff has potential energy. If the rock falls, the potential energy will be converted to kinetic energy.
Elastic Potential Energy
Elastic potential energy is stored in stretched or squashed materials such as rubber bands or balls.
Some objects can change shape reversibly. Rubber balls, springs and elastic bands are like this. When a rubber ball is stretched or squashed, it can regain its original shape, proving that they have elastic potential energy.
A stretched spring in a pinball machine has elastic potential energy and can move the steel ball when released.
Light energy (sometimes called radiant energy) is transferred as a wave after being released by an object. It can be absorbed or reflected if the object it hits cannot absorb it.
It is the only form of energy that we see directly.