Physics Graduate EXPLAINS Physics Paper 1 2023 GCSE Science

hey guys welcome back to another GCC science video this time this time we're going to be doing physics paper 1 from 2023 and again the point of this is for me to walk through my exact process on how I would approach the questions as well as try and teach you the content as well um I will say with a lot of science a lot of it is just kind of practicing the questions so doing exam questions on PMT and doing past paper questions as well but it is helpful to have an understanding so you can actually learn the content rather than just try and memorize it because memory is a very fickle thing um before we get started most of the people that watch these videos are not subscribed so if you do find anything that I've gone through useful then please do consider subscribing is it does help I also have the link to my website and my email address in the description in case you want to ask about tutoring or literally anything else but let's just get started with question number one so we start off with the National Grid and power and all of that kind of stuff so wi power and solar panel are both renewable and they used to generate electricity for the National Grid which of the following is also renewable geothermal natural gas nuclear fuel well both both of these use fuels which means they are not renewable or at least they're not considered renewable whereas geothermal just uses the heat generated from the Earth itself so in kind of volcanic areas especially because there's lots of magma and things like that uh under the ground the energy transferred by the National Grid in 1 second was 36 gigles which is absolutely crazy which of the following is the same as 36 G and it gives you a bunch of standard form so here learning the these prefixes is very difficult and those of you that want to do a level physics they come back and again is a little bit tricky in short you have just your normal units whether it's Jewels or meters or um kilogram actually no sorry not kilograms grams things like that and then as it goes up it goes to kilo so for example if you think of meters the next thing you have is kilometers which is a th meters then you have mega uh megameters we you probably wouldn't have heard of much but if you think about phone storage or storage on computers you have kilobytes megabytes and the next thing is gigabytes and these are 10 to three each time you go up you just increase the power by three so if you'd like it goes up in powers of a th000 right so this is you have one Jewel 1,000 jewles a million jewles one GJ or in other words 1,000 kles is 1 megga and 1,000 megga is 1 G however you want to word it so in other words we're looking for the one that has 10 to the 9 which is the third option moving on so now we have how power varies they do like to ask this because again they want you they want to test your understanding of renewable versus non-renewable resources and how it's changing over time that's the kind of key takeaway from this to understand that we're trying to move towards more renewable energy sources so here is this shows how the mean power output from solar and wind varies between 2014 2019 and as you can see it's a a general upward trend for both wind and solar and then figure 2 shows how the power output from solar and wind energy varies in a typical year so this isn't any specific year this is just on average if we have a look at this quickly it should hopefully make sense with solar it Peaks around June July time which makes sense because that's the hottest time of the year right the brightest time of the year and with wind it decreases at June and July because it tends to be less windy and then it Peaks during the winter because that's when we tend to have really strong winds likewise solar it is lowest in the winter months because that's generally where we have the least amount of sunlight again this is just a typical year it's just an average here is the actual kind of year-by-year data so explain the changes in power output from solent wind energy resources between 2014 and 2019 and include an explanation so there's a key word here of the change in power output during a typical year and it also says explain the changes now there there is some confusion between the word explain versus something like state or describe if they say describe or even State they literally just want you to say what the change is so for example I could just say every year the amount of wind power has increased or over between 2014 and 2019 the amount of wiow increased and the solar Powers increased as well and again described would just be okay the wind power decreases uh towards Summer and then increases at the winter and vice versa for the solar when you explain you need to State and describe as I've just done but then you need to say why that happens so essentially I've given you three of the six marks but just so you're aware you do need to have an actual explanation as to why this is the case so what we're going to do is every single point that I just made we're now going to explain it so the first thing I stated or described is that uh wind power so between 2014 in fact let's type this between and then let's move this over between 2014 and 2019 the amount of wind power has increased so that can give you a mark just stating the TR Trends only gives you two marks okay so you need to actually explain what's happening so why is this happening we simply put um it could be there's two main things but more wind farms uh were built right that logically makes sense there is also an explanation as to kind of things like climate change making um wind more strong essentially or having more stormy weather again I would stick more to the whole more wind farms were built because that's more concrete this is more of a a theory so again this this year or at least back in 2024 they did mention how he had loads of storms over the winter and they did mention that could be as a result of climate change and things like that so that is a valid thing you can say so that was the first thing we said the second thing we said was between 2014 and 2019 the amount of solar power increased now you might have noticed that it increased at kind of a lower rate so if you look it's a lot more consistent I would say but again all we're focus on is why and why is that simp again you can say literally the same two things more solar panels were I don't really want to say built but I guess that would be the word I think deployed is the technical term but let's just leave it as that and again you can mention climate change in the same way again you need to say that climate change makes you know the sum more bright essentially so that's basically it for figure one again we have a point exclanation point explanation that is the key key thing now for figure two so I'm going to leave some space we need to base again what I described and why so you can say a variety of things here you could say wind power is always except in June and July more of an output than solar and then you can describe why so it could be that the UK is more windy than it is sunny which I would 100% believe but you can also just say that there are more offshore wind farms in in fact I'm going to bet that's the real reason so we have lots and lots of offshore wind farms around the UK which because they're offshore they have unobstructed wind so it's a bit more consistent but let's just um I think we should focus more on the fact that wind power is at its minimum during the summer months and we can explain why and solar panel power is at its peak during the summer months and we can explain why so during a typical year wind power is at its actually no its lowest during June July why because it is less windy in the summer in the UK and then we can also say during a typical year solar power is at its highest during June July because the sun is brightest in these months and that is more than enough so again we have kind of four points and we've gotten an explanation for each of them I will go through some of the other ones where it's I mean yeah you can say the intensity is greater or the amount of sunlight is greater you can say that um winter is windier than summer if you want to explain why it's at Peak any of those is completely fine but I would recommend just sticking to essentially stick to what you know and what you can can explain so don't try and be fancy with it stick to what really really makes sense to you and that way you can explain it better which means you're more likely to get those marks but remember when you're explaining it you need to give concrete cause and effect so why is there lower wind power in June and July because it's less windy okay you can't say something a bit more obscure moving on to question two fairly quickly we have body analysis scales use the electrical resistance of a person's legs to determine or sorry estimate the percentage of water in the the person's body this is what they look like the person's legs contain both solid tissue and water a student used resistors to model the solid tissue and water this soon connects their 20 oh resistor in parallel with resistor R and this is the circuit diagram they came up with to determine the total resistance of both resistors so again let's highlight that the total resistance a volt meter must be connected into the circuit complete figure four to show where the volt meter should be connected now here's the key thing if they want wanted to know the resistance of R then you would connect it like this and I've this is where a lot of students kind of went wrong so if you're want to work out the resistance of R then yes you would use the voltmeter in parallel with just the one resistor the unknown one and then you have the current from a and you use V equal I the thing is they want the total resistance of both resistors now I know you're probably thinking well can you just use the resistance of R and use the addition rule in parallel to work work this out yes but why not just measure it directly so again the markeing does specifically say voltmeter symbol correct and connected across the resistors plural so be careful with that the student calculated the total resistance to be 26 ohms explain why it cannot be correct so again when it says explain you want to State the problem and then explain why that's the case so 26 ohms if we go back to our diagram here they're saying the total resistance of both of these is 26 ohms why cannot why can that not be true well here's what we're going to do I want to pretend that R was 10 just as an example how would you work out the total resistance well what you would do is you'd say one over the total resistance is equal to 1 over 20+ 1 10 so that' be what 3 over 20 right because you times this one by two by the way this is a calculator exam so you can just use calculator which means the total resistance is 20 over3 what you'll notice is no matter what the resistance is here whether it's 100 a million five whatever the total resistance is always less than 20 ohms and this is because when you add them you add the reciprocal so in other words it cannot be greater than 20 so resistance cannot be greater cannot be greater than God my shaky hands greater than 20 ohms why because the total resistance in parallel is because res resistors added in parallel reduce the overall resistance that that's the reason why and again you can explain this in a few different ways so but again that's the general idea again one of these calculation questions which total four marks which I think is really really nice and it says use the physics equation sheet to answer the next two parts write in the equation that links i r and v that is of course Oh's law which is V equal i r super super nice when the total resistance of the resistors was 7.5 the current was 480 milliamps so that's 480 * 10us 3 again think of this in terms of meters right millimeters are a thousandth of a meter which you can also write 0.48 if you really really want to calculate the potential difference well again we're just using vles IR again this is why I absolutely love these calculation questions because it's just using your equation sheet finding the right one so in terms of how can you work out which equation you need to use well firstly 2.3 right they give you the symbols so you're looking for an equation that has i r and v in it cool and here again they've given you R they've given you I and you want to work out V so you're using the exact same equation but again you need to label what you have look at your equation sheet and just find whatever expression whatever equation has v i and r in it so let's uh stop yapping and let's actually get on with this so 0.48 multipli 7.5 gives me 3.6 and again for three marks that is pretty pretty damn good in my opinion for the next part here we have the student investigated how the resistance of R affected the total resistance in the circuit so again just just to show you that changing this value changes the overall resistance again as R gets bigger it should get smaller um so overall here the the Gap is getting smaller but the actual total resistance is getting bigger of course it says sum of the results so since it's a sum I'm willing to bet that the question is finish plotting the graph which is fantastic complete figure five you should label both axes plot the two remaining values and draw the line of best fit cool and you basically get one mark for each of these so labeling the axis is quite nice if you're not sure what should be on the X or Y AIS you can cheat so if I look at this first point it's five and four so if I look here five is the resistance of R and four is the total resistance so you can use that and say well that means this side must be the total resistance because the point is 54 right so it's on the y- axis so that's quite nice so resistance of R and then we can say that's in ohms and then on the left side or on the y- axis total resistance also in ohms and again that's just because the coordinate we have is five is the resistance of R which means this must be the resistance of R and four is the total resistance there which is quite nice quite a unique way of of finding out how to do that the two values missing for 15 and 20 so let's quickly do that 15 is 8.6 so 15 and it looks like it goes up in tws so 8.2 4 six in terms of how you work that out okay terms of how you work that out all you do is you look at how what is the gap between the two values so the Gap is two and how many squares is it there's one 2 3 4 5 6 7 8 9 10 which means each Gap should be 2 over 10 which is 0.2 so 8.2 8.4 8.6 8.8 9.2 9.4 9.6 9.8 10 so it does work and the other value was 20 and 10 yeah 20 and straight on 10 in terms of the line of best fit um honestly this is pretty tricky for me to do on a computer um but I'm going to do my best I'm going do my best so um essentially there's a few different things here and then this is where things get a bit tricky firstly in a normal question you would just line up your ruler and just see how you can get through the first and last point with most of the values um being either side so for example if I draw a straight line from here to here this is not correct by the way before someone starts writing an angry comment please there we are and what you ideally want is you want an equal number of crosses below and above the line so if this was hypothetically our data this would be a good line of best fit if you notice though no matter where you put your ruler you can't actually get through these points you can't get through enough points and there's a reason for this remember what I said at the beginning the gap between these numbers is getting smaller so it's 2.7 it's 1.9 then it's 1.4 then it's 1.1 so in other words it's curving off so this line of best fit is actually a curve of best fit so you just kind of want to draw I'm actually so impressed with that that is not bad okay I'm actually really impressed with that but it's a curve instead so again normal circum cumstances you line up your ruler so that way there's an equal number of points above and below the line however if you notice that when you again so line up the first and last points and try and angle it so there's an equal number above and below if that's impossible let's say all of them are above the line or all of them are below the line it means you have a curve instead so if all of these points were on the bottom instead you would curve upwards that's how you can tell what it's going to be but the key thing is line up the first and last points completely fine and then just see if it's a curve or if you can fit a straight line in there cool this is what resistance of R would give a total resistance of 4.4 so all you're doing is using your amazingly drawn expert uh graph you learn the best fit so 4.2 4.4 is here so I'm going to draw a line going across again I would ually ruler in normal circumstances read it [Music] down what the hell does this go up in that is a good question but it goes from 5 to 10 that's of five and it does that in 10 so that is in FS so that is 5.5 ohms nice and neat so the body analysis scale initially shows a reading of0 kilos the student steps on it says 64.8 they step off then immediately step back on it says 64.1 complete the sentence the difference between the two values given um two values given by the scales is due to a something error that error is a random error so here's a really good problem why is it not a zero error this is really really important and I think this question was deliberately designed to trick people the reason why it could people might think it's a zero error is the idea is that when you step off and step back on the value is now different the problem is a zero error is specifically when let's say when the you know initi shows a reading of if it says initially shows a reading of -1 kilo or- 0.5 or plus 0.25 or something that is a zero error the idea is that when there's nothing on the scales it's not reading zero that's a zero error and this can also be true for things like voltage as well if you connect your voltmeter in parallel and there's no electricity but it gives you plus or minus some number like maybe it gives you 0.05 orus 0.1 or something that's a zero error the same is true for digital thermometers for scales and all sorts the problem here is they step on step off then step back on and it's different that is a random error because again they haven't shown us any evidence to say that when no one is stepping on it it gives a number that's not zero so the fact that it tells me it's zero at the beginning means it cannot be a zero error a zero error is only when there should be be a reading of zero but it gives you a different number so the most obvious example is with scales if you have a set of scales and it says .5 kilos but there's nothing on the scales that's a zero error in and of itself I hope that makes sense I've said the word error so much it's kind of losing meaning to me now but hopefully that makes a bit more sense to you guys the height of the student is programmed into the scales the scales place the student into category a b or c based on height and mass figure six shows how the scales use the category and the total resistance of the legs to determine body water percentage because water is not a very good conductor so um so it's not a very good conductor but it's a lot better than your bones and your muscles and stuff so we have these categories okay perfect and it says the total resistance of the student's legs is 600 kiloohms so that would be right here on our graph a healthy body water percentage is between 45 and 65% 45 seems ridiculously low but fair enough the different measurements of the mass mean that the student could be in A or B evaluate if the student has a healthy body water percentage so here's what I would do I would find what their body water percentage is if they were in a and b and I would determine if that means they are healthy or not so uh let's read it off so 600 kiloohms let's go up and we'll read off a first that's let's say that's 60% and if we read off B that's 68% okay now let's read that condition again it's between 45 and 65 so in other words if they're in category a they are healthy if they're in category B they are unhealthy and that's it you know what I'm actually want to change that to 61 cuz I'm pretty sure if I zoom in that's actually 61% okay so yeah all you have to do is write those three bullet points so if the student is in category a their body water percentage in fact let's move this over now water percentage is 61% in fact we can do this in two bullet points if we are absolutely Geniuses if if the student is in category B their body whoops body water percentage is I think it was 68% God my memory is awful Isn't it yeah 68% which is unhealthy and right there we have evaluated it right we've said well it depends if they're in category a their body water percentage is 61 which is healthy if they're in be the body water percentage is 68% which is unhealthy so again in the mark scheme as long as you say category a 61% category B 68% then you say if it's healthy and unhealthy you get the full three marks which I think is quite nice I've seen this question so many times I actually stopped recording and looked up on the channel to see if I've done this paper before that's how many times I've seen this question they love absolutely love giving you this question um again because the whole National Grid thing is a big part of the spec it says it shows how the National Grid transfers energy from a power station all the way to some Street lamps eventually how do the Transformers X it says explain increase the efficiency of the National Grid the key thing here is to say what the hell they do in the first place and then how does this make the efficiency better so the first thing is these are step up Transformers when you step up it means the voltage gets bigger so they increase potential difference now in order to make sure that the power stays the same because conservation of energy right you can't just create infinite power that means current decreases now the key thing here is think about why this is important this gives you two marks again you would have to write increases PD you can't just do it in shth hand like I'm doing why do we do this specifically to reduce the power lost due to why is heating so when you have a large current going through something it it heats up the cable or heats up whatever it's passing through so if you decrease the current by increasing the potential difference it reduces the amount of energy lost due to that thermal heating which also means we don't have to replace the cables as frequently because heating up uh wires damages them shockingly I know which is why you have to replace filament bulbs by the way because the wire in the middle of them gets destroyed over time okay this calculation I will say is actually somewhat tricky so it says the potential difference let's call it V I'm going to call it V 1 and V2 and the current in the primary coil is 660 calculate the current in the secondary coil now there is an equation sheet for this which says something along the lines of Ip VP equals is vs sometimes they put the V first instead so V VP VI VP I equals vs I um but in any case the reason why this works is they're basically saying the power should be the same on both sides of the coil which again conservation of energy right it' be very weird if the power changes because then we could just infinitely change it to make more and more energy which doesn't make any sense so essentially this is just the power in the primary coil is the same as the power in the secondary coil but we can just sub this all in and and work stuff out or we could work out the power in the primary coil and then just divide it by 11,000 volts whatever you want to do is completely up to you but um we be easiest let's just sub it all in so the potential difference in the primary coil is 400,000 and that's Times by 660 amps which is absolutely insane then we have 11,000 Times by the current in the secondary uh coil so just divide both sides by 11 11,000 which again would be the exact same if you did it the other way did it the other way God my voice died there for a second equals I'm not going to do that in my head so we have 400 1 2 3 * 660 over 11 1 2 3 gives me 24,000 amps that's um it's pretty high I mean that would definitely kill you uh which is fun uh why is the current in each Street Lamp less than the current in the secondary coil well hopefully that makes sense if 24,000 amps were going was going through the um each Street Lamp that would be pretty uh intense so why is it that it's not the same well if you go back up you may notice something about the diagram here is these Street lamps are well actually you know you probably wouldn't really know this so we know and it does say here we know that the current in the Street Lamp is less than the secondary coil now why might this be the case well think about what causes current to decrease in a circuit that's what I would be thinking about so you could say current is used up in the cables that is very minor it would not result in a significant decrease at all some of the currents disat to the surroundings again it would not be significant enough the cable again that basically all three of these say the exact same thing it's because the street lamps are connected in parallel every Street Lamp that you connect in parallel will divide the current so if there's two Street lamps it would half it if there's three Street lamps it would divide it by three if you think about how many Street lamps are in a in your local area it's probably hundreds of them I would imagine maybe even thousands um actually stick with hundreds which would reduce the current to like a a more human level where you won't just like it explode if you touch it or something so yes it's the last one because when you connect things in parallel it divides the current going into each one here we have an example of the top of a Street Lamp where we have a light sensor and we have lamp the light sensor detects if it's day or night and it does this by having a light dependent resistor essentially how light dependent resistors work is the brighter it is the more light hitting it the lower the resistance which means this resistance will increase so explain what happens to the potential difference across r as the light intensity decreases well it says explain right so we can't just say it increases or decreases we have to explain why now the first thing I'll would do is I'll think this through in my head if this light intensity decreases it means the resistance here increases which means the I mean honestly I'll probably just say that this voltage decreases but um you could also say that the the current also changes or decreases or whatever you want because of the over power and then all you need to do is write that through so again the end result is voltage decreases that's your answer but I need to explain it so I would write resistance in ldr increases hence um current decreases which means potential difference across R decreases so essentially it's just your your rule of a potential divider when the current in the resistor R is 20 milliamps the power transferred is 6 Watts calculate the resistance of R for four marks using the physics equation sheet if you've noticed they normally break this into two parts find the equation then you do a calculation in this case they've just made it all in one part the equation you're looking for again we have I we have p and we want the resistance so we looking for something that links p i and r which is p is equal to i^ 2 R if you weren't sure about that you could use p = i v and then v = i and sub it all in but you know I like to keep things nice and simple resistance then is just P / i^ 2 p is 6 I is again you could say 20 * 10-3 or you could say 0.02 remember Millie is a thousandth of um and that would be squared as well that was that was a close mistake on that we get 6 over 0.02 s and we get 15,000 ohms which is kind of a lot that's kind of big kind of huge a scientist investigated a sample of radioactive material to determine if it would be suitable for medical use the method results and conclusions of the scientists will need to be checked by other scientists before the results of the investigation are published what is the name given to this process well the first thing is it's a type of review right if you review something you check to see if it's if it's functional if it works you think about like tech reviews on YouTube or movie reviews what do they do they look at the whole thing and they check it and they give a real technical analysis of it now if it's checked by other people who are also scientists what you call them you can call them colleagues but you more call them peers so it's a peer review because they're on the same level as you so for example everyone doing GCS this year are your peers even if you don't work with them or even if they don't go to the same school because you're on the same level okay so a colleague is someone that you actually work with a peer is someone that's on the same level as you so all teachers in the UK are peers as an example there's an increased risk of cancer if the scientist is irradiated by nuclear radiation what property of nuclear radiation caus The increased risk it is ionizing because what it does is it ionizes atoms in your DNA which causes problems with protein synthesis um which leads to potentially cancers the activity of a radioactive source is the rate at which nuclei of the source Decay what is the unit is the Beckel or BQ again where one Beckel is literally one Decay per second so normally this is a very large number the scientist placed a radiation detector near the sample measured the count rate explain why the count rate is less than the activity of the sample this is interesting so there is a reason why we use count rate and activity you can work out the activity from the count rate and functionally they actually measure the same thing they measure the number of decays per second but with count rate if you think about it when you have a let's call that uranium and you have your detector here it looks like a camera radiation will hit the detector and then it would say that is one count right and then every time that happens it's a count the problem with radioactivity is it goes off in every direction so you're only measuring the radiation that actually hits here now you can use some fancy maths some really cool geometry in order to work out the actual activity for all of this but the idea is you only get radiation from One Direction hitting it that's why the count rate is less than the activity because radiation spreads out so not all radiation emitted is picked up by sensor is h no let's say detected let's let's be you know Fancy by sensor because um radiation spreads out essentially now of course you could say well why don't we just surround the whole thing in detectors and the answer is that's kind of expensive and annoying and also it's very hard to make a sense that's 100% coverage because it mean the entire surface would have to be a sensor so instead it's honestly really simple maths on how you can work this out I'll be curious to see if any of you can work out how to do that uh think about which shape it's forming when it spreads out but you can work out quite easily what the value is so we don't bother just surrounding the whole thing in senses here they give us the count rate from the sample and distances so here we have distance in centimeters so 2 5 and 10 and the count rate drops exponentially like absolutely massively in fact you you kind of two and a half times the distance and it's basically gone to under a tenth of its initial value about 9% then it goes down to zero so which explain which type of radiation well firstly this is just happening in air right there's nothing they haven't put any kind of material in front of it this is just in air the only radiation that's blocked by a small amount of air is Alpha radiation and then again it says explain why so you get one mark for saying it's Alpha why because it's not detected Beyond 5 cm or because all the radiation is um stopped within 10 cm or just simply Alpha radiation is shorts range in air that's probably the way I would put it anything along those lines implying that Alpha radiation is stopped by air will get you the final mark this is an interesting question um I quite like it actually but it is quite tricky the scientist moved the detector closer and started a stopwatch and he measured the count rate so as you can see the count rate is still decreasing even though it's the same distance because as it says here the scientists realized that 30 minutes is a whole number of half lives so interesting essentially uh a halflife is the time it takes for the count rate or the activity of a radioactive sample to half right half life uh another way to describe it is it's the time taken for half of the nuclei to Decay anything along those lines so in other words to go from this to 60 because this is a whole a whole number of Half Lives 60 is also a whole number of Half Lives because it's just double right so if that was let's say two half lives this would be four this was three Half Lives it would be six and so on um but it means that essentially if we keep halfing this eventually we'll find out how many half lives it takes so that's what I'm going to do I'm going to keep halfing this number until I get to 98 to see how many half lives that is so you can do a fancy trick you can press equals because this is basically iteration divide by two we get 784 so that's one half life two half lives three Half Lives four half lives so it takes four Half Lives to get from 1568 to 98 which means to get from here to here because it's only it's half as much time it would take two half lives I probably should have written down what two half lives is oopsies actually we could go back so that's three Half Lives that's two half lives so the answer should be 392 um counts counts per second for three marks that's pretty nice I think but again knowing to do that is quite tricky because geometric sequences just in GCS maths are quite tricky and not a lot of students know it in fact if that was taught better this question might be a bit easier but you know is what it is right scientist had a second sample of the radioactive material he made appropriate measurements then calculated the half life of each sample why is the half life calculated from the sample slightly different from the half life calculated in the first sample um if we honestly process of elimination here the count rate is predictable I'm going to say not really because radioactive decay is a random process right it can't really be predictable the samples at different temperatures no because radioactivity decay is random there's actually no way to increase it so if you have again uranium just as an example the top of my head it doesn't matter how hot it is it will always well it will have roughly the same count rate so temperature will not affect that the size of each sample again the size doesn't affect count rate as weird as that might seem it is actually because radioactive decay is a random process a student measur the maximum height reached by the toy oh forgot about this part so yeah they're basically pushing down the spring letting go and the the spring the toy goes into the air cool place a vertical meter roll next to the door and observe the height to reach by the toy St repeated the experiment observing from a different position so we have this one this one apparently this affected the measurement how well the reason is parallx error because in this case when he's reading the measurement he's looking up and so as you can see he goes above whereas here he's moving it looking about there so essentially when you read something off if you are not completely level with it you're going to read the wrong answer so you could say actually one sec says effect in the measurement um okay explain how essentially because he's reading from a different angle so he is reading the measurement from a different angle and position B is more accurate the reason why I want to say that is because well a it's a two mark question so we need to give two points ideally um but the other reason is we're saying it's different okay so what which one's better so again imagine you're a teacher in this case and you see a student doing this versus this you wouldn't just say oh you're going to you have a difference because of the way you're reading it it's like okay thanks sir or Miss so you say well this position is actually better cuz you're more level with the actual toy ideally he would be perfectly level with it but obviously that can be quite tricky which is why you might want to use like a camera setup instead or something along those lines the greatest height reached by the toy is 64 CM I going to put that into meter straight away because we are scientists we use proper units the gravitational potential energy is 0.049 Jew gravitational field strength is 9.8 calculate the mass use the physics equation sheet the the equation you're looking for is that the energy is equal to M GH in this case the energy is 0.049 the height is 64 and G is 9.8 so if we wanted to work out Mass I would just divide both sides by GH so we're doing 0.049 and we're going to get an absolutely disgustingly small number actually yeah it won't be that small I suppose certainly won't be big though so let's do that 0.0 whoops 49 over 9.8 * 6.4 whoop well wait it'd be great if I could read um so that be what 0.0078 I guess we can call it I would say probably giving it in grams makes more sense right so 78 G I'll say that makes a bit more sense yeah five marks man like it's pretty good it's pretty good not bad at all and lastly for part three when the spring launches the toy into the air the temperature of the air increases explain why the charged toy on its own is not a closed system well they've told us why remember a closed system is one where energy cannot leave it so if this was a closed system when the spring extends when it gets launched into the air all of the elastic potential energy in the spring would go to gravitational potential energy moving it up but it says here the temperature of the air increases which means the energy of the air increases that's why it's not a closed system because energy is being dissipated to the surrounding air which means it's not therefore total energy is not constant so again with a closed system the total energy would not would not change because all of the elastic potential energy goes into kinetic energy or into um gravitational potential energy and that's it but here we have energy being lost to the surroundings If energy is lost to the surroundings it's not a closed system final question we have a device that shows a mug of hot coffee using sorry using used to turn a wheel so we have the hot coffee there's an air chamber connect to a piston which okay cool the hot coffee increases the temperature of the air in the chamber explain how the pressure in the chamber changes okay so again this is explain how so the first thing I'm going to do is I'm going to State what's happening when temperature increases the pressure in the chamber increases okay that's just a fact increase in temperature always results in an increase in pressure now we have to explain why the reason is because the particles in the air have greater kinetic energy hopefully your teachers have told you that temperature is basically a measure of kinetic energy of the particles inside something so essentially the hotter something is the more they're moving the faster they're moving around the faster they move around means that they collide with the container at a greater speed so all more Force particles collide with chamber with greater force and hence pressure because remember pressure is just force per unit area so if Force increases pressure also increases assuming that the area doesn't change for the device to work the air in the chamber must increase in temperature quickly explain why the bottom of the air chamber is made from metal than plastic so we have the hot coffee here the bottom here is made of metal rather than plastic and they tell us that the air in the chamber must increase quickly so why is it made out of metal well we need to link those two facts they wouldn't tell us that the pressure sorry the temperature must increase quickly unless it was relevant and now they're saying why is it made of metal than plastic well simply metal is a better conductor of heat by the way my uh eeky is um kind of broken of heat than plastic okay so there is a faster increase in temperature because of energy transfer that's it so again in the question they have to give you the information you need or you have to be able to kind of figure it out so the fact they told me the temperature must increase quickly is relevant to this question because they wouldn't have told me otherwise okay explain why the bottom of the air chamber is made of metal rather than plastic so metal must somehow increase the temperature faster than plastic how could that be because it's a better conductor the mass of air in the chamber is constant what property of air allows a small change in internal energy to cause a large change of temperature so with linking here change in energy linking to change in temperature which of course is the specific heat capacity because if you remember the specific heat capacity is the amount of energy required to increase the temperature of 1 kilogram of a substance by 1 degree so a small change in energy causing a large change in temperature it's the fact that it has a low honestly you can't just say a specific heat Capac capacity but if you want to be more specific you could say the fact that it's a low specific heat capacity because the lower the specific heat capacity the easier it is to heat something up the changes in pressure in the air chamber cause the wheel to turn so just one way to increase the speed in which the wheel turns um loads of different ways it says the change in pressure right so you could say that you use a um hotter coffee cuz the higher the temperature the faster it will turn but also you could lubricate the wheel itself so that way you're not losing energy due to friction in that case this looks like a fun question a six Mark calculation man oh my God what is this a matte paper so the temperature of the coffee decreases as the device is used of course cuz it's heating up the air the initial temperature of the coffee is 76° C the internal energy decreased by 15 K so we've got an energy here here we've got a temperature we've got density we got volume we got the specific heat capacity so I'm assuming that it's the question that we had before equal MC delta T or equals MC Delta Theta I think is actually how it's given in your equation now if we have a look the question says calculate the final temperature well that means we're going to work the out the change in temperature and then we're going to apply that to the fact that the initial 76 so if the change in temperature was 10° then the final temperature is 76 - 10 cuz it goes down cool now if we have a look at this if I rearrange this for our Delta Theta we get e over MC we have e and we have C but we don't have M now if we think about M for a second what information have they given me that I haven't used yet because remember my Golden Rule they never give you information you don't need well they've given us the density and volume okay we need mass and we have density and volume what equation links density mass and volume well it's density is mass over volume so mass is density time volume and we have density and volume so now we can work out the mass of the coffee and plug that in so we have that mass is equal to density which is 1.1 * 10^ 3 you can put this in Brackets but you don't actually need to which is another really useful thing about um standard form the volume is 1.9 * 10- 4 if that seems small don't forget it's in me cubed and that gives me 0.209 and then we just plug in the rest of the values so the change in energy was 15 kilj juels kles so that's 15 * 10 3 or it's 15,000 however you want to do it the mass is 0.209 and the specific heat capacity is 4,200 which is basically the the same as water which kind of makes sense cuz coffee is basically just water 15 * 10^ 3 over 0.209 multip by 4200 gives me a change in temperature of let's call it 17.1 de actually no you know what we write out the whole thing degre Celsius which means the final temperature well if it starts off at 76° and we know the temperature is decreasing because it's says the internal energy decreased so the temperature decreased means we're going to subtract the value we just got and then I'm going to round that to one decimal place 58.9 de celsi you know what the temperature is in degrees here let's just round it to to SF that's it that was a that's one of the harder calculations you'll have to do bear in mind that now you've done it once you should be able to do pretty much any specific heat capacity question right which is the good thing about science is that the calculations are very very similar every single time but again label what they give you write what you need and then think about okay why have they given me this information how can I use it that's the questions you should always be asking yourself in these questions it applies to maths as well um but especially with science it also works really really well but that brings us to the end of the paper finally um not a bad one I would say but again there's a lot of stuff there that has a bit of nuance to it and of course I mean I have a degree in physics so of course this stuff isn't too tricky to me um but yeah if you did find that useful then please do consider subscribing it really does help but hopefully that was useful to you and I'll see you in the next one