Energy - 1.1.1 Energy Stores and Systems (GCSE Physics AQA)
Energy Stores and Systems
What are Energy Systems and Stores of Energy?
In physics we often used the word ‘system’. A system is an object or group of objects.
Whenever we talk about systems, we are simply referring to the object(s) that we are looking at. For example, if we’re talking about the process of evaporation of a hot pan of water, the energy system would be the whole pan including the water, the actual pan, and the heat source.
We can have two types of energy systems: open or closed.
Open Systems
Open systems are able to exchange energy and matter with their surroundings. When you boil water in a saucepan, heat energy is able to leave the system in the form of steam. As this energy gets transferred, the system is changing.
Closed Systems
A Closed energy system is unable to exchange energy and matter with their surroundings. When you pour coffee into an insulated thermos flask and close the lid, heat energy is unable to leave the system. This means that you have created a closed system, where no energy or matter can be transferred.
Energy Changes in a System
We have already mentioned that when a system changes, energy is transferred. When this energy gets transferred, it will go from one energy store into another.
There are 8 main types of energy stores that we need to know for AQA exams, which are shown in the table below. We will go into more detail into each of these stores of energy later on.
Examples of Energy Changes
- Flying – an object projected upwards.
When an object is projected upwards, such as a ball, it will initially have kinetic energy (KE). As the object rises higher into the air, the kinetic energy will be transferred into gravitational potential energy (GPE). Once the object reaches its highest point, the gravitational potential energy will all be converted into kinetic energy as the object falls back to the ground.
A moving object will start off with kinetic energy. Once it hits an obstacle, the kinetic energy can be transferred into many different types of energy. It can be transferred to the surroundings as thermal energy and sound waves. Some of the kinetic energy of the moving object can even be transferred to the obstacle, causing it to move.
When an object is accelerated by a force, there is a transfer of energy. Firstly, energy is required to accelerate the object; this could be chemical, thermal or electrical (the situation will determine the specific type of energy). This energy will then be converted into kinetic energy (used to accelerate the object).
This scenario is the opposite of the last one; we are now decelerating. Therefore we will work backwards from the previous example. To slow down the vehicle, the kinetic energy of the movement will be transferred into another store of energy. This energy could be sound waves and thermal energy.
When we are heating up water in an electric kettle, we are transferring electrical energy into thermal energy, which is used to heat up the water.
Energy Changes in Different Contexts
Students often get mixed up between different sections of the Physics course because we talk about similar concepts. One of these is work done. Work done is equal to the energy transferred by an action. We will learn more about this later, but it can be applied to different topics.
In the topic of electricity, work done means the amount of chemical energy a circuit is converting to electrical energy, or the amount of electrical energy a lamp is transferring to light energy.
In the topic of forces, work done could be the amount of chemical energy an action (e.g. pushing a trolley) could be converting into kinetic energy.
In the topic of heat, we may talk about energy transfer from the chemical energy in a bunsen burner, to the kinetic and thermal energy of particles in a water bath
Principle of Conservation of Energy
For your GCSE exams, it is important to understand the principle of conservation of energy and the law of conservation of energy.
Throughout these topics we will be looking at different calculations to look at the amount of energy transferred. Normally we look at closed systems, so the total amount of energy in the system stays the same. So when we look at energy transfers, the energy before must equal the total energy after (e.g. a light might convert 100J of electrical energy to 70J of light and 30J of heat energy).
What is the law of conservation of energy?
The law of conservation of energy states that energy cannot be created or destroyed. Energy can only be transferred rom on type to another. In other words, the total amount of energy does not change.
FAQs
Energy is the ability to do work. It can take many forms, including heat, light, sound, and movement.
The different forms of energy include kinetic energy, potential energy, thermal energy, light energy, sound energy, electrical energy, and chemical energy.
Kinetic energy is the energy an object has due to its motion.
Potential energy is the energy an object has due to its position or condition.
Thermal energy is the energy of a system due to the movement of its particles. It is often associated with heat.
Light energy is the energy of electromagnetic radiation, such as visible light and ultraviolet light.
Sound energy is the energy of a mechanical wave, such as sound waves in air.
Electrical energy is the energy of an electric charge or a flow of electric charges.
Chemical energy is the energy stored in the bonds between atoms and molecules. It can be released through chemical reactions, such as burning or digestion.
An energy system is a collection of components that work together to produce, store, and transfer energy. Examples of energy systems include electrical power grids and batteries.
Still got a question? Leave a comment
Leave a comment