in today's video we're going to be looking at topic one of GCSE physics and that is the energy topic please make sure to pause and take notes where you can to make sure you're as prepared as possible for that GCSE exam if there is anything in the video that you want explained a little bit further comment it down below and I will do my best to answer you as quick as possible but apart from that I hope you enjoy and let's get to it first of all we have the different energy stores so as you can see in the red box there are eight different energy stores that you need to remember for this topic kinetic thermal gravitational potential elastic potential chemical electrostatic magnetic and nuclear some are much more common than others and the ones that you recognize are probably the ones that you need to know a bit more about most of you will know that there are equations linked to some of them which we will get on to a bit later on in the video as well there are three main different ways that energy can be transferred between these different stores so as you can see at the top I have an example of a tennis ball being dropped from a height onto the ground now at the top the tennis ball is at rest so it has no kinetic energy all of the energy that it has is in its gravitational potential energy store now once you let go of that ball gravity does work on it and pulls it down now in that time the height is being decreased so the gravitational potential energy decreases as the kinetic energy increases because it's speeding up once it reaches the bottom at a height of zero just before it's about to hit the ground all the energy that was in the tennis ball at the start has now been converted into the kinetic energy store that is just one example I would recommend you get familiar with plenty of examples and are able to explain the energy transfers going on there let's have a deeper look into kinetic energy here is the equation 100 you should be familiar with this equation before going into your exam E equals half MV squared and as you can see underneath I've written the word equation and the units that you should be familiar with as well gravitational potential energy we have E equals MGH or mass times gravitational field strength times height and again the units below gravitational field strength can alternate between Newtons per kilogram or meters per second squared be careful when talking about the units depending on what the question involves normally and then we have elastic potential energy very very similar to kinetic energy and this relates to when things are being stretched or compressed so for example an elastic band is going to have a certain spring constant of the material and then the extension depending on how far you stretch it the spring constant changes depending on what material you're using so everything will have a spring constant but you can imagine something like an elastic band is going to be a bit easier to stretch than something like metal so always bear that in mind but you will never be expected to know the values they will always give you the questions and most of the time you'll just be substituting them in here we have specific heat capacity a very important definition to remember specific heat capacity is the energy required to increase the temperature of one kilogram of a substance by one degree Celsius and all substances have a different specific heat capacity just like with the spring constants that we talked about a minute ago there is also an equation you are given this one in the equation sheet the change in energy equals the mass times the specific heat capacity which is denoted by a c multiplied by the temperature change the specific heat capacity does have some interesting units so that might be a good one to remember if you're ever unsure you're actually able to rearrange the equation to get specific heat capacity on its own and then from there you can work out the units depending on what equation you have if you want me to make a separate video on that please comment down below and I will do so the conservation of energy arguably the most important thing in all of the energy topic energy can never be created or destroyed only transferred usefully stored or dissipated now an interesting point about this is using this Theory all the energy that we have in the world today is exactly the same amount of energy as we had when the world and the universe first began we have just found ways to use it in more of an effective and efficient way power so power is the rate of doing work as the equation shows anything that's to do with rate is often to do with time because if something happens a lot quicker you would say it's a quicker rate you'll notice that energy or work done could be on top of this fraction so take that into consideration when it comes to your exam questions they could use work they could use energy both mean the same thing so don't worry about over complicating it next we have conduction and convection this is all to do with how heat moves through matter so conduction occurs in solids and as you can see from the diagram the particles when they get hot they vibrate and that energy that they create from vibrating is transferred across the solid until all of them are vibrating which makes the whole solid hot convection occurs in liquids and gases so as you can see I've tried to model more of a gas here when all the particles are closer together this is representing a hot area and just like the fusion all the particles spread out to fill that container which makes the whole container hot so just like when you're at home you put the heating on or you have a fire on the gas particles around the fire or from the heating Source are going to be hot first but then over time it heats the whole room or the whole house here we have efficiency and reducing unwanted energy transfers a lot of these methods you will see from your house so cavity wall insulation Loft insulation draft excluders and things like double glazed Windows you might also hear that things like carpets can help reduce this but that's all kind of Fairly common knowledge and things you can normally see in your house on the other side we have an efficiency equation the efficiency equation looks a little bit more complicated but if something is efficient then the energy that you put into it will convert it into the thing you want out of it so when you simplify it down into words it can make a little bit more sense to you our total input is going to be the bottom of the fraction and the thing that we're interested in is the useful output so let's say you put 100 watts of power into a light bulb but you only get 80 Watts out of the light bulb of light that means that 20 watts of that energy has gone to heating or maybe sound but it just shows it's not going to be a fully efficient light bulb and as that point at the bottom says nothing is always 100 efficient and there is always something being dissipated within it we're nearly at the end but we have energy resources so renewable and non-renewable you should be very familiar with at least four of those on that list if you can't name all six it's not the end of the world if you can amazing and you should also have a rough idea of how they all work so things like solar panels provide solar power wind turbines are for wind believe it or not hydroelectric would be from things like dams biofuel is organic matter and animal waste and stuff like that tidal is from the tides so geothermal often occurs from places that have a lot of volcanic activity which produces a lot of naturally hot water as you can see underneath I've written pros and cons of both renewable and non-renewable so renewable energy resources will never run out because we can renew them they do less damage to the environment they do still do some damage because obviously for example building a dam to provide hydroelectric power is going to disturb a lot of habitats and stuff like that um however they can be unreliable so for example if you're in the UK it's not as sunny as it would be somewhere else so if it's not Sunny then you can't get any solar power from that on the other side we have non-renewable energy resources things like fossil fuels so you should be very confident with those three and also nuclear is quite a commonly forgotten non-renewable resource and again you've got the pros and cons on that side fairly similar to the renewable ones just kind of the opposite and finally we have the National Grid so the National Grid I will let you read that stuff in the red box will be very important but as you can see on the diagram the factory will produce this electricity and then we use a Step up Transformer to increase the voltage which will basically make less resistance in the wires so less energy is lost to heat as it travels through it will go through the pylons through the country and then a Step Down Transformer is used where it decreases the voltage again and goes back to the houses where the power is at a safe amount to use within a home and that is the end of the energy topic the next topic I will make a video on for physics is going to be the electricity topic so wait around for that one but thank you very much for watching and I hope that helped