Physics Graduate Makes Physics Paper 2 EASY 2021

hey guys and welcome back to another GCSE Science video this time we're going to be doing a physics paper 2 because physics paper 2 kind of sucks it's kind of tricky but before we get started most people that watch these videos unsubscribed so if you've ever found any of these useful at all please consider subscribing as it really does help me out um also if you want I have loads of spaces in my gcsc science and gcsc maths classes uh if you're interested in joining those tuition classes please check the link in the description and lastly my email address is in the description in case you have any questions about GCS or what never at all but without further Ado let's jump straight into this paper and try and walk through it as best we can so the first question we have a stretched spring which is elastically deformed and it says what is meant by elastically deformed now there's two types of deformation that you need to know about in GCSE one is plastically deformed and the other is elastically deformed and what's the difference well I like to stick with elastic because I think that elastic is something that's fairly it's a word that's used a lot in day-to-day conversation what does elastic mean well if you have an elastic band so a rubber band or you have like trousers that have an elastic band in them what does it mean means when you stretch them and you let go it goes back to its normal size right so if you get a rubber band you stretch it you let go it pings back together right that means that is what the definition of elastically deformed is it will return back to its original shape when the force is removed so it's the last one so what's plastic deformation or plastically deformed that is when you're using something something like Play-Doh for example it's when if you squish it or you compress it it does not return back to its original shape so if I take something like a a plastic bag or I take Play-Doh or something like that and I squish it up and I let go it doesn't revert back to its original shape it stays deformed that's when it's been plastically deformed now all objects will have a little bit of elastic deformation before it becomes plastically deformed so with the spring if you ever had a slinky may have seen this but if you have a spring in your pen for example if you stretch it really really far eventually it will not return back to its original length you have then plastically deformed it so hopefully that makes a bit more sense describe a method to determine the extension of the spring so here we have our system this is a very common practical which I'm hoping that you've all done but it ask us to work out or state a way of measuring the extension now how do you measure the extension well hopefully you've done this before but the idea is you first measure the original length measure original length oral length and then measure the extended length so what do I mean by that well let me go back to the top and show you what I mean you would take the mass off and you just have a spring that's dangling you'd measure its length let's say it's 50 cm for argument sake then you hang your mass on and you measure the new length let's say 60 cm your extension is the difference between those lengths cuz it's gone from 50 to 60 cm and then all you do is you do extended take away original and that is how you work out the extension of any object and here we come on to the first calculation the extension of the spring is 80 mm the spring constant essentially telling you how stiff the spring is is 40 Newtons per meter so it takes 40 Newtons of force to stretch the spring by a meter calculate the elastic potential energy of the spring use the physics equation sheet the equation that you'll be looking for is the energy is equal to a half K x^2 where X is the extension now you need to be careful with the units here K is in Newtons per meter so we leave that 40 but the extension is in millimet so I need to change that into meters now how' you go from millimeters to meters well what I would do is I would go into CM so you divide it by 10 so 8 cm then divide it by 100 to get to M but that is what you'd be doing for that and again you should get quite a small number so let me just open up my calculator so 0.5 or a half depending on what you want to do and then 0.08 squared which is 0.128 Jew of energy which isn't a lot but it's not really meant to be a lot cuz it's just a spring after all for three marks I think that's a pretty reasonable thing especially because the equation is on your equation sheet you just need to be able to find which one it is this is a really common question in gcsc science exams where they ask you to get an equation which links three or or however many variables and then in part in the next part they ask you to use that same equation so here the equation the way I call it is FAL KX where X is the extension but they've said here they want to use the letter e for extensions so the actual answer would just be k e so on your formula sheet it may give you KX instead and you just need to change that to K now it says a force of 300 Newtons acts on a different spring the extension is 0.4 M find the spring constant well if f equals k e then if I divide both sides by E that means f e equal K so means K is equal to the Force 300 over 0.4 so that's 2 F which would should be 750 let's have a look 300 over 0.4 750 and then what are the units actually we don't need to know because the question gives it to us Force but it is a good practice to kind of get used to thinking about what units are in the odd case that they do not give them to you professional rugby players wear a tracking device that measures their velocity and their acceleration figure two shows a player with a tracking device so apparently it's just on their back on their shirt probably the player is tackling another player is running with the ball velocity and acceleration of both Vector quantities what is a vector quantity uh honestly this is just a definition it is a quantity that has magnitude and Direction so we're not just talking about the size of it so for example 10 jewles of energy we're also talking about which direction they're moving in so for example these players may have the same Vel same speed but their velocity is in opposite directions because they're moving in opposite directions this if any of you want to do engineering or anything like that in the future or maths or physics vectors are going to be your bread and butter they are very very very useful in real life then says which of the following is a vector quantity tick one box which is quite nice cuz sometimes they just say tick all that apply uh distance is just a length so it's not that one time only doesn't have any direction work done is energy and energy is not a vector because you just say 10 Jews or 100 Jews you don't kind of imply a direction you also can't have negative so that's something else about Vector qu uh sorry scalar quantities is they aren't negative we don't have negative time right we don't say that took you 10 seconds to do with work done or energy we don't say that's 50 Jew with distance we don't say oh you know on a ruler you don't measure -5 CM but displacement absolutely can be negative because it's distance from a point so you can have positive and negative displacement that's just another way to think of it here we have a velocity time graph for the player Running With The Ball determine the acceleration of the player between 0 and 1.6 seconds so when you have you know velocity time graphs or even speed time graphs or even uh displacement time graphs you do need to work out a few different quantities from it the way I do it is when I work out gradient here I'm doing velocity over time if you notice acceleration is just velocity over time so the gradient of that line is going to give me the acceleration if I times the two quantities I found the area underneath the graph that's velocity time time which is distance or in this case displacement technically but whatever so that's the way I kind of think about it I think if I times the two quantities what do I get if I divide them what do I get dividing is gradient timesing is the area underneath so determining the acceleration between 0 and 1.6 well the velocity starts off at zero so I'm going to put zero there and it ends at four so we have four takeway Z over 1.6 takeway Z I should be able to do this in my head but I'm not going to 5 over two so 2.5 uh m/s squ for two marks I think that's pretty reasonable but again you need to use those tricks you know finding the gradient finding the area which one makes the most sense for what you need to do with something like this it's always going to be either the area or the gradient if it's acceleration it's always the gradient of the Velocity time graph 4 2.4 describe the motion of the player between 3.4 and 3.6 so 3.4 is this point here and 3.6 is this point here so as you can see they are decelerating and because it's a straight line whoops that means the gradient is constant which means the acceleration is constant which means this is constant deceleration you can say constant negative acceleration that is totally fine because technically we don't have deceleration technically or large deceleration or something along those lines would would work the next three parts uh we have again a very stereotypical calculation question where they first say hey what's the equation then you're going to use the same equation this is very very common pattern so the equation that links acceleration mass and resultant force that is Newton's second law Absol classic absolute Banger of an equation FAL Ma and then it says the player accelerates at 25 m/ squared which is ridiculously fast when a resultant force of 1,00 Newtons acts on her calculate the mass of the player well if we have FAL Ma and you know we have F = 18800 Mass we don't know but we know a is 25 a then that means a is just equal to 18800 / 25 again I should be able to work this out but let's just uh leave it as is shall we uh 72 kilog and lastly but certainly not least we have the tracking device sends data to a computer during the game so just one advantage of the data being sent during the game well this these types of questions are very hard for students to answer and they're very hard for teachers to answer as well because they require using you know a lot of empathy which sounds a bit weird but you have to put yourself into the shoes of the people doing this so why do they want the data in the first place well to be honest I don't know much about sports but you know you I guess the only reason why you'd want the data is because you want to monitor the players right you want to see how well the players are performing during a match okay so why is it good or why is it an advantage to send the data during the game as opposed to well we see what the only other option it's after the game right well if it's during the game then that means you can monitor the performance during the game monitor the performance live as opposed to having to wait until afterwards so you can imagine that the coach maybe is looking at this data in real time or whoever looks at the data I actually don't know to be honest I guess like a phys physiotherapist or something uh will be looking at this data whilst the game's going on which means they can give immediate feedback after the match that would be my guess but this is kind of the the idea so you need to kind of break it down so first of all why do they need the data well they're obviously monitoring the players for some reason I don't know the reason I'm going to be honest with you uh maybe it's for injuries maybe it's for how they can be more efficient whatever right then it says an advantage of it being sent during the game well what's the opposite what's the only other option well sent after the game right it can't be sent before the game because the game hasn't happened yet so why is that an advantage well the only difference between sending it after the game and during the game is one is live and one is not live so that's why I've written the answer monitor performance live and in the mark scheme it does say performance can be monitored during the game so potato potato same thing okay so for question three we have waves which again is a pain in the butt topic for a lot of students so student made water waves in a ripple tank and as you can see I've drawn an excellent one toone Recreation of this so we have the water tank and we have these waves they will appear dark patches especially if you put a light underneath it which is what a lot of people do to make a Shadow but whatever describe how the frequency and wavelength of the water waves can be measured accurately so first things first if you want to measure wavelength I like to think of the units so frequency is measured in per second or Herz and wavelength is me measured in meters so what we're going to do is we're going to start with the wavelength CU I think that that's a nice place to start we're we're going to place a meter ruler along the side of the tank like this and we're going to measure the full length of the tank so Place meter ruler uh it's probably best to say like along the wave fronts or perpendicular to the wave fronts perpendicular to wavefronts those black lines are wavefronts by the way and we're going to measure the length of the screen measure length of screen measure length of screen all we're going to do is that the wavelength is equal to the length of the [Music] screen divided by the number of complete waves now I'm going to explain this to you of whoops complete waves what we have here the black lines are the Peaks and the reason for this is if I show you what this looks like from the side it' be something like this so I'm going to try and match it up as best I can right these Peaks here are the black lines which means between them is you have the the troughs right the the parts of lower displacement hope that makes sense so far now if you remember what wavelength is is the distance between adjacent Peaks or adjacent troughs so all you need to do to work out the number of complete waves is you go one 2 3 4 5 6 you basically just count the number of pairs of black lines that's it and then when you're dividing it that just gives you the length of one of them which is uh which is the wavelength the frequency is a bit more interesting uh don't forget as you're doing this these waves are constantly moving so to do this first part You' most likely either need to take a photo or I guess you could do it normally if you managed to create standing waves but yeah yeah let's leave it as that for the frequency here's what you need to do the first thing is is in per second what do you know of that counts seconds well we're going to use a stopwatch right because that counts seconds that gives you one of the marks now how you going to do this what you're going to do is you're going to record and count using the recording waves passing a point each second so if it's five Waves per second then the your frequency is going to be five Hertz and that's literally it um yeah that that's basically it so I hope that makes a more sense now the St recorded values for the frequency and the wavelength of waves in the Ripple Tank table one and two show their results we've got the frequency in Herz 9.8 9.4 9.3 then wavelength in centimeters 1.7 2.2 and 2.1 it says determ the mean wave speed now uh in order to do this all you really need to do is first of all we need to write the equation which is V is equal to F Lambda we are going to have to convert this Lambda into meters because don't forget we want the answer in meters per second and now when it says the mean wave speed that's because they have three values now I'm assuming that your science teachers have been very good which it's a bold bold statement I know but we need to uh calculate the average of these because the whole point of taking three readings is that you can average them afterwards now I will say this looks a bit anomalous but it hasn't said that there's any anomalies so I'm going to just say I'm just going to work out the average for each of these for this one it should just be 9.5 right but let's say you didn't know how to didn't know didn't know that the mean is you just add up the values so 9.8 + 9.4 + 9.3 and you divide it by the number of values in this case three let's see if I right 9.5 so the average there is 9.5 Hertz let's do the same for the centim so we have 1.7 + 2.2 + 2.1 / 3 we get 2 so 2 cm for the wavelength which again we need to convert into meters by dividing by 100 and then all we're doing is doing 9.5 time 0.02 which is something and we get 0.19 me/ second which again bear in mind that this is a water wave right so it's not exactly going to move super super fast or anything it's water um yeah that's it for four marks which I think is fairly reasonable I think this is one of the harder calculations because you have to do the mean first but remember if it says mean and if they've G or if they've given you three different readings you need to work out the average cuz that's the whole point of getting three readings right hopefully your teachers have shown you that in every experiment that you've done so this is a really really good question kind of at the heart of a law of science what is the advantage of taking repeat readings and then calculating a mean the idea is to reduce the effect and it is important that we say the effect of random errors uh the reason why I say reduce the effect is because random errors are random we can't actually predict them right because they're random that's the whole point point and so we can't guarantee that taking a mean of three values gets rid of the random errors at all but it will reduce their effects because since they're random let's say for example in these values here this is 0.1 bigger because of random error this is 0.1 smaller and that's 05 bigger because they're in different directions some of them make the numbers bigger some of them make them smaller they cancel each other out a little bit not entirely or at least we can't guarantee it'll be entirely but they will at least a bit the speed of the wave is affected by the depth of the water in the Ripple tank this is not something you're expected to know the deeper the wave the fast sorry deeper the water the faster the wave explain how the depth of the water affects the wavelength if the frequency is constant so again this isn't necessarily something you would know but they're relying on you being able to use science use the equations we've got to make predictions so they're talking about the deeper the water the faster the wave so in other words velocity is increasing but it says that the frequency does not change so how does it affect the wavelength well if V increases but F stays the same Lambda also has to increase the wavelength also has to increase I mean let's think about it right if V goes from 2 to 3 but F stays the same Lambda has to increase right there's there's no other way so in other words wavelength must increase because of this because of that formula there that's what you need oh boy probably the least fun part of physics I'm just going to point something out by the way gcsc everyone hates magnets a levels everyone hates magnets when I was at University doing my degree everyone hates magnets magnets suck and they are honestly they're not that well understood really there's a lot of kind of missing information about them so if you are interested in doing like physics and things like that magnets are very odd and so they might provide some kind of interest to you but yeah everyone hates electromagnetism it's it's a universal thing even at University even the you know grum field professors magnets suck but we have a magnetic field pattern and it says where is the magnetic field of the magnet the strongest now if you've ever used a magnet like played around with it you might know this just from experiencing it right just messing around with it yourself but here's how you can tell the closer together these magnetic field lines are the stronger the magnetic field so if I look over here I have five lines packed together but over here I have three lines that are quite spread out and over here again it's like two lines that are quite spread out so in other words where are the lines the closest together they are the closest together at the poles now the reason why I won't just say the North Pole or the South Pole is because at both poles they have kind of an equal field strength so all you have to do is right at the poles and again that is entirely dependent on how close together the field lines are then says how does figure 4 show that the strength of the magnetic field is not the same at all places well it's just what I just said the strength of the field is how close together the field lines are so why is it not the same everywhere well if you notice look at the distance between the field lines it changes everywhere so it gets further apart in different places so we have to do is say because the distance between field lines varies between field lines berries that's why the magnetic field strength is not the same everywhere the the strength of the magnetic field is not the same everywhere because the distance between the lines changes figure five shows an electromagnet being used to separate Iron and Steel from nonmagnetic Metals explain one reason why an electromagnet is used instead of a permanent magnet so it says explain one reason so what that means is you're only saying one positive but then you're saying why it's a positive okay so some people try and give two different reasons and they think it'll give them two marks it won't it will give you one mark because they're asking for one reason and an explanation so what I like to do is I like to have a bullet point what's the reason well what's the difference between an electromagnet and a permanent magnet the only difference really is that you can turn off an electromagnet that's it turn off an electromagnet right that's kind of the key point now why is that useful well what were we trying to do with this so we put this electromagnet over a conveyor belt and all of the magnetic Metals so in this case they're just talking about Iron and Steel will get stuck to the electromagnet whereas the rest of the metals just go off to wherever they're going next so of course the problem is eventually it's going to get full right then too much metal on the electromagnet so we need a way of removing the metal from the electromagnet right logically well the easiest way is to turn it off because when you turn it off it'll just drop that's it I like to think of it almost like you have a a claw to grab something right so you have this hand and it grabs stuff from the conveyor belt but if it can't open again it's kind of pointless because then you have to break it to kind of let go of the thing you have to use a lot of force to open up the the hand again so to speak or the claw so the purpose of this is to easily remove the Iron and Steel afterwards that's the point hopefully that makes a bit of sense then says pieces of iron and seel are attracted to the electromagnet name two other metals that would be attracted uh there's a few but probably the most common ones are Cobalt and nickel so given that the design of the electromagnet so the actual shape of it cannot be changed give two ways in which the force exerted by the electromagnet could be increased so if you remember you have a few equations like you have for example b as an example now since they're saying that the actual design cannot be changed that means the well B can't really be changed either nor can the length so we could increase the current in the electromagnet the next one's a bit trickier because as we've established we can't change the field strength we can't change the length we have to change the current but what else could we change well simply put we could bring the electromagnet closer closer to the uh conveyor belt because then the iron and still are closer which means the force is stronger because as we know as you get further away from a source of a force it gets weaker things like uh electrostatic and gravity and things like that here we are the motor effect or the generator effect depending on how you want to look at it people hate this people really really hate this but the conveyor belt that make that moves the pieces of metal is driven by an electric motor which is um it looks exactly like this where you have an alternating current going through this which spins the wire because it's in it's between a magnetic it's in a magnetic field the length of the wire AB is 120 mm so I like to label that L don't forget we want to change that to meters so that would be 12 CM or 0.12 M God the current is four and the force is 0.36 calculate the magnetic flux density which is B so we're looking for an equation that links FB I and L that is force is equal to Bill uh which means the magnetic flux density is force over i l and we just sub in the values for five marks five five marks crazy absolute Insanity uh i l so let's do 4 * 0.12 uh so that would be 0.36 over 0.48 that would just be 3/4 0.75 I'm pretty sure 0.75 but let's not be arrogant we have a calculator so let's use it oh too easy now that actually gives us four marks because we have to give the unit so as I said earlier they do not always give you the unit so what is the unit in this equation it is the Tesla so capital T Tesla and for the last bit we have an absolute classic the thing you know we throwing up gang signs in the exam with the different forces and stuff we have Fleming's left hand rule which can be used to determine the direction of the force on The Wire AB complete the labels so how do I do it well there's a few different ways um this is the second finger right and if you notice it has a c in it so second is the current finger the first finger you know it starts with an f and so that is the field lines or the field you know the magnetic field is what I'm trying to say here uh for the thumb I don't really have a really good one but it's like a it's a force um I have heard it said as like the thumb since it begins with th it's called the thrust but I don't know about that that's a bit weird doesn't really make sense to me but yeah first finger is the for uh field second finger is the current thumb is the force um yeah that that's just how I do it to be fair if you have the two others then you just know the the last one is the force that's just the way it is I like the second finger being the current the first finger being the field and then it's just the other one is is the force um in the future if you guys do a level physics or even University level physics you have a right hand rule as well but you can actually use this for any sets of related vectors which I think is pretty cool so now we're going back to the electromagnetic spectrum and we have different parts used in medical imaging cool and we have this infrared camera which basically detects temperature change as you can see here so the dark bits are like 23 degrees which is uh let's just say room temperature and it goes all the way up to 34° which is apparently the temperature of this dude's hand at least three of the fingers the other two are a lot colder which is interesting probably due to blood flow I'd say explain why the infrared camera is able to show that parts of the hand are at different temperatures so this comes to what is infrared radiation infed radiation is released from hot objects so infrared radiation or different temperatures temperatures release different amounts or intensities whoops forgot to write different different amounts or intensities we should really use the word intensities because we're being very scientific of infrared radiation so essentially hot objects release a lot of it and cooler objects do not release as much of it so you know when you're very hot so maybe after you've just done a lot of running or something like that you've been out in the sun for a while you can sometimes like feel the heat coming off your skin that's infrared radiation whereas in like the winter for example you're very very cold now this difference is picked up or represented on the camera um differences are represented represented as different colors or Shades as different should we say shades or colors I want to say colors because it goes from black to white unless you consider black and white Shades which maybe it's a color gradient right um yeah that's essentially how it works it's very useful in different conditions so uh some people use it for like picking up the presence of human beings in buildings if there's like a building collapse or something like that they sometimes use infrared cameras to try and pick that up um and various other things this is the bit that I lot of students I have trouble with infrared has wavelengths from 700 nanom to 1 mm uh so 1,000 nanom basically which parts of the electromagnetic spectrum would have waves with a wavelength of 6.5 * 10us 7 any pretty much anything with time 10us 7 is visible light uh it's It's Tricky it's very tricky to know all of these I don't really think people should have to learn all of these because it's a bit arbitrary but it's part of the spec it's something you have to do but the good news is there's normally only one Mark to do with it in each paper and here's a big one uh in hospitals we tend to use x-rays which I'm sure most of you will either have very soon or have had in the past the reason why I say we have very soon is when you hit 18 uh when you have your last dentist appointment for free on the NHS they take a x-ray of your mouth to kind of have a track of your position of your teeth and things like that um but they also use gamma rays which I doubt most of you will have had before uh which is handy so for x-rays uh machine produces a brief burst of X-rays and that's it produces a picture which is basically the same way as how a camera Works where has a flash of light and it produces a picture we have a flash of x-rays which produces a picture for an x-ray at these gamma rays however you need to inject a radioactive isotope into the blood and the gamma rays will come out of that radioactive isotope as it passes around your body so the idea is you can then see the exact blood vessels going through a person whether it's in this case it looks like it's in someone's leg they this a lot for uh Imaging the brain and the heart as well um because those tissues do not show up very clearly on x-rays so instead we need to use something else uh this is really really useful because it shows you it it traces blood vessels so you can see if there's any internal bleeding or if there's any kind of aneurisms or something like that super super super useful but compare the potential risks um obviously with so I'm actually going to type this just to make it a bit easier in terms of comparing the risks both have a risk of ionizing radiation right they both have risk of cancer due to ionizing radiation so xrays ionize your DNA as do gamma rays and so they both can cause cancer that's just a a sad fact of life uh what else well when you think of the x-rays or as or with gamma rays essentially with gamma uh radiation the whole body is irradiated whereas xrays um only affect kind of the the exposed part so what I mean by that is when even though this gamma this gamma Imaging technique here is only for this person's leg it looks like the knee because you're injecting it into the blood the gamma radiation is all over your body because we can't I mean when you inject something into your blood it only takes a few seconds for that to pass completely around your body continuously releasing gamma rays with an x-ray they normally only need an x-ray of a very specific part so here it looks like this woman's abdomen so maybe her spine or something like that or her rib cage so you can basically keep the rest of the area covered right her head is not going to get any x-rays her legs aren't going to get any x-rays same with when you get that Dental scan when you're 18 it's only going to affect your head right or your teeth it's not going to affect your chest your legs anywhere else so in that case there is less exposure in x-rays than there is in gamma rays because the gamma radiation has to pass around your entire body so the radioactive isotope has to pass around the entire body um yeah so that that's kind of a big thing and the last thing that you really need to say is that the exposure time for gamma rays is longer sorry for the double ease by the way I think my keyboard's broking and it's starting to type random amounts of e the reason why I say the exposure time for gam is longer is this procedure here takes a hell of a lot longer again when you do that Dental scan if you've ever had x-ray before it is extremely quick we're talking about seconds like the do the dentist or the doctor will leave the room flash done that's it whereas with this machine here it takes an image over a much longer time scale and of course even if this Imaging didn't take that long you've still injected radioactive isop into your blood so even after you've left the Imaging machine or whatever or even the hospital you still have some of that radioactive isotope in you uh the reason why I've only put three bullet points even though we' had four is technically this is a second Point x-rays only affect parts of the body so we've kind of done in three bullet points four marks worth of answers for this question here we have x-rays are produced by colliding high energy electrons into a metal Target which is very cool electrons have high energy because they're accelerated to very high speeds but only a small portion of the kinetic energy is converted into an x-ray because the rest is is scattered off or released as other types of energy and electron is accelerated through a distance of 15 mm so that's distance the work done is 1.2 * 10-3 work out the force so we have f w and D that is work done is equal to the force time distance so that means force is equal to work done over distance which is going to be a very very small number over 15 okay we could write this as * 10- 3 or we can change this into cm and then change it into met so let's just do that because I don't want to oh there's another zero Mitchell come on there we are again some of these equations you just have to kind of know but I do think that the most effective way to learn the equations is obviously to have whoops have a formula sheet in front of you whenever you're doing questions and label the variables they give you and the one that you want and then all you're kind of doing is looking through the formula sheet for an equation that has the three or four or whatever letters that you have so f w and D if you look on the formula sheet wals FD that's it so it's kind of like a uh a treasure hunt I guess kind of 8 * 10us 12 Newtons again I love the calculations in GCSE Science very nice assuming you know the equations but hopefully now I've shown you a way of how you can find which equations you need to use now the metal Target is usually made from tungsten because it has the highest melting point of any metal so why does this enable the x-ray machine to be more powerful well again look at what they've given you they've told you it has the highest melting point that must be relevant so in this case well if you imagine you're hitting this metal over and over and over and over and over again the metal is going to heat up It also says enables the XR machine to be more powerful so that means the xrays are stronger which means the electrons are hitting it even harder harder and harder and harder well as you can imagine some of the energy from the electrons is transferred to the metal which means it heats up the metal so I mean basically I've just given you the three Mark answer already so some energy from electrons oh God come on Heats Heats I'm pressing the E first I promise you heats up the metal so some of the energy from the electrons heats up the metal which increases the temperature of the metal so using a higher melting point metal enables more electrons to be collided per second than a different uh metal which would melt that's basically it it's pretty cool pretty cool so here is a very interesting question this is the last question but it's only two parts because each part is worth a lot of marks so scientists are developing a Hypersonic airplane that travel much farther faster than normal airplanes an airplane accelerates from a low speed to a high speed with the engines at maximum power but the acceleration is not constant why well the the forward force of engines is constant so you might think well hang on that means the acceleration is constant but think about what happens now as you speed up the overall force that we use in fals ma is the resultant Force so we're going to have the driving force of the engine minus well what force is opposing airlanes when you're moving through the air it's a resistance so I know that this part is constant the driving force is constant but the air resistance will change so as velocity increases the air resistance also increase this reduces the overall you know resultant force on the plane which decreases the acceleration of the plane so as this plane speeds up the res the air resistance will increase this means this number here the driving force minus the air resistance decrease increases which means the acceleration decreases I should probably add because mass is constant so the mass of the plane should also be constant but yeah that's the essential reason so although the driving force is constant the overall force acting on the plane is not constant because as it speeds up the air resistance the air is trying to stop it more and more and more the air resistance increases which means the acceleration will drop they give us a lot of information here the Hypersonic airplane will have jet engines and a rocket engine uh the speed is measured on a uniform scale called the moach scale basically mock 1 is 330 m/s this is just the speed of sound so mock is how many times the speed of sound you're going so this is 5.5 times the speed of sound that's 25.5 times the speed of sound which is crazy um and the resultant Force calculate the mass so we're we're going to be using f ma whoops but all they've given me is they've given me a change in velocity a time a force so we don't have the acceleration but remember acceleration is just the change in velocity over time so that has how would we write this 25.5 minus 5.5 but then we're timesing it by 330 right because that's the actual speed that it's going at so that's 20 * 330 which is 6,600 over 300 seconds so that's the acceleration right so we have 25.5 again that's the actual speed the difference in the MOX times 330 over 300 gives me 22 m/s squared which is actually really really quick then FAL Ma so that means m is equal to force over acceleration which is 630,000 over 22 I don't know the answer to that I'll be honest 630 23/ 22 okay we're going to round this to two significant figures so we look at the second nonzero number which is8 the number next to it is bigger than five so we're going to make that 29,000 kilog which is yeah that's pretty heavy it's not that hard right it's not rocket science get it rocket science rocket engines okay so um that brings us to the end of the paper uh I think that paper is pretty good question six is definitely very hard the calculation is a bit of a monster but again label what they've given you label what you have and label what you want I didn't actually label what I wanted in that case and then look at the equations you have to try and work things out I think that that is very difficult but I hope that uh explains things a bit better for you I hope that that makes a bit more sense I hope that gives you more confidence if it has again please be sure to uh subscribe because it does really help me or like the video share it Etc all that fun stuff but I will see you in the next one best of luck in your revision