 Okay, we're live. I'll start out first of all by saying, I think the plan here is I'll take any questions you have from the review, trying to go through the whole unit. There's only about four or five lessons, which it overlaps so much. I think it's easier if I do any questions from here. So starting out, we're learning from the big review that you tried that you look at my answer key that you were wondering or wanted me to go over. Yo, 23. Sure. So this is an interpret graph question. We did do a short little lesson on that. And I said, look, it's either going to be the slope or the area, almost always. Student plots the graph below showing the kinetic energy, ek versus the square of its velocity, v squared. And it's asking me the slope. First thing I'm thinking is I have an equation that has both of those in it. Right away, Alex, I thought to myself, oh, hey, why don't I copy this? No wonder I can't write on this clip. First thing that I did is I thought to myself, if I've got an equation with ek and v squared in it, why don't I write it out? Kinetic energy, and I use ke instead of ek, you'll see y in a couple of units equals a half m v squared. Is that okay so far, Alex? Then I asked you what the slope is. Well, slope I said is rise over run, but it's really saying, okay, rise over run, rise of 20,000 over a run of 400. What does that work out to? 50. But then it asks what the slope represents. Okay. Well when I go rise over run, what I'm really doing is I'm dividing energy by v squared. I'm going to write this as k energy, ke over v squared, and what do I have left over on this side? The mass of this object of this motorcycle was 100 kilograms. Had to have been, because the slope is half the mass. Had to have been. Is that okay? Then there's a part c, I think. Using the axis below, sketch the graph of kinetic energy versus velocity. Now v squared just velocity. Okay. What did your graph look like when you graphed y versus x squared? You know what ke versus v squared is going to look like? It's going to be half a parabola, the right hand positive half of a parabola. This also makes sense because when your velocity is zero, what's your kinetic energy? So it's got to go through zero zero. I can figure out that much. And what they're asking is do you remember your math 11? Now what they did on the graph above Tyson is because they wanted a straight line, they didn't graph v on the x axis. What did they graph instead on the x axis to straighten the graph out? v squared, which will give you a straight line. It's just a different set of data points. Okay. That's a good example of an interpreting graph question. There's definitely going to be one of those on your final and on a couple of your tests. I haven't found a good one for every one of a unit test, but there'll be some in the future you'll come across. I'll give you a graph and I'll say, hey, tell me what this means. It's either the slope or it's the area. Slope, divide the, either the units or this time I divided the variables because that was easier. Area, multiply the units or multiply the variables. Is that right? Because it's kinetic energy equals a half mv squared. It's the equation because I wrote it right up here. So what they're saying is, okay, what if we didn't graph v squared? What if we graph v? What'd that look like? Wouldn't be straight anymore. It'd be a parabola. Is that okay? Next. Number 15. Did you look at my answer key? I may do it or I may pause and say read. Okay. Ah, 15 I'll do because I think I like this question. A toy car, oh, a .03. They did give me the math. See it right there? Right there. It's pushed against the spring launcher. Oh, and they not only gave me a, they gave me a distance. Good. And what other data did they give us? They gave us this bit of information here. A, what's a asking me to find? So work is force times distance. And the most common mistake kids make here, Nicole, is they go, oh, a force is 20 and the distance is .9. Look at your force. Is your force constant or is it increasing? Look at this graph. You're telling me the force is 20 newtons along this whole graph? Sorry, what? And I'm going to say Nicole, I think that's obvious now. Yeah. Get a spot that. I can't use force times distance, but I gave you a definition of, another definition of work. I also said, so I'm going to go, uh, I also said it's the area under a force versus distance graph. What kind of a graph did they give me? Hello. There it is. Okay. Work is going to be this area, that area. What shape is that? What's the area of a triangle? Now it is on your formula sheet, but I'd like to think at this stage, you know it. Cheers. Base times height divided by 2. What's my base? It looks like it's .09. Careful. There's an extra zero there. Yes. What's my height? 20 divided by 2. How many joules of work did we do in compressing this car? Spring. Nicole, stop. Look up. What's 20 divided by 2? What's 10 times .09? Why is that wrong? A lot of the energy ones will work out fairly evenly. So check your sig figs. Yes. Joules. So far so good, Nicole. B. What maximum speed is reached by the toy car when it's released? Well, we just did work on the car. We stored energy in the car. And you know what? All of this energy is going to become kinetic because we had another definition of work. Work was also the change in potential plus the change in kinetic. Mr. Dewick, you really have a tough time making capital E's. They're hard for a lefty, especially on this slippery screen. Look at your diagram. Is there a change in potential at all or does that surface look pretty flat? Yes. Why the hesitation? Okay. Look at the diagram. Does this surface look pretty level or is there a change in height occurring here? I think I can reasonably then say, and what's changing? What's your initial speed? So I think this, the work is just going to be your kinetic energy final. Is that okay? What number is this, Nicole? What question number was this? 15. And we're back. I just had to stop and get some people organized and then I lectured them. Nicole, you're back here. Hey, what is kinetic energy? This is really convenient because the question asked us to find the maximum speed. Well, if work equals a half mv final squared, I think there's my v final. See it? See it? See it? If I get it by itself, I think it's going to be times by two divided by m and square root. Yes? I think v final is going to be two times the work divided by the mass. Do I know the mass? I think that's in the diagram, not the graph, the diagram at the top of the page. See it there? Yes, yes, yes. And do I know how much work is done? That's why I needed to find the area. Okay. What do you get? Two times 0.9 divided by, what's the mass? The mass is 12.2? 0.03. Square root of 60? No. Yeah, I'm right. Yes? No? Really? Okay. Gotta get beyond calculator mistakes, right? I'm getting 7.75, 7.75 meters per second. Are we there? Yes, yes, yes, yes. What's C asking? If what? So we did this much work. If it all got changed to kinetic, that's how fast it would be going. How much got changed to kinetic? That much. Efficiency, I said, well, efficiency is going to be, remember the symbol for efficiency was that funky thing, but if you just write EFF, I'll clue in, or efficiency, I'll clue in. It's always the smaller number divided by the bigger number, 0.18 divided by 0.9. How do I know those numbers go together? Well, the number they gave me was in joules. It's the number on the bottom. Better be in joules, otherwise it's nonsense. What do you get? Oh, and then times 100 to make it a percentage. Did you say 20%? Yeah, technically 20% efficient. Where'd the other 80% go to? Sound, energy lost due to friction, heat in the springs, other stuff. Is that all right? Next. It's number 18, the waterslide yucky one. Okay. This one I will explain. This one, this is in my top five toughest questions all year. This is probably on it, okay? Which is good. This will be the kind of question, if you're shooting for 100%, and I mean 100, not 99, I mean 100, I'd expect you to get this. If you're shooting for 90 or higher, I'll expect you to follow my explanation. If you're shooting for 80 or higher, I'll expect you to get the gist of my explanation. The rest of you, I'll expect you not to drool. Okay? Ready? Basically it's saying, if you double the height, how far out will it go? I started out by saying, well, if they want DX, the range, I know from unit one, the range is VXT because AX is zero. So I wrote that down, and I said, what is VXT going to be? Now I said, the time is going to be constant. The reason the time is going to be constant, the time of flight has nothing to do with how far sideways you go. It's how far you're dropping from in terms of a height, and it looks like we're dropping from the same height each time. Is that okay, Andrew? Okay. So when you roll something off a table, it's in the air for the same amount of time, whether it barely falls off or whether you roll it really fast. It's just going to go farther based on its VX, but the vertical drop time is still going to be the same. So I said, what this question is really asking me is this. What happens to that? I said, well, there's a curvy path. There's a change in height. I'll try solving this using energies. Oh, and I got really clever. Nicole, for the rest of this question, I put the ground at the bottom of the slide, so that final potential energy would be what? Zero. And initial kinetic is what? So when I, oh, ma'am's canceled, very nice. I said an expression for the velocity is 2 times g times whatever height you release it from, square root it. That's from a height of h. That's v final. Just wait and watch. Copy this down later, or print it up later, because every time you look down, you're missing stuff and I'm having to wait. Okay? You okay with where this came from so far? What if we double the height? What if we put a 2 in there? What if we put a 2 in there? I replaced the h with 2h. Well, I said, you know what? I've added a 2, but where is the 2 inside what? Square root. I said, really, all that's happened is not an extra 2. An extra root 2 has appeared. This is my original final velocity. See it? If I double the height, I get an extra root 2 in the front. So I said, you know what? Doubling the height, it doesn't double your velocity. It increases it by root 2, which means the distance is also going to increase by root 2. That's the algebraic way to do it, Trevor. You know what else you could have done? I'll let the height be 5. What would 2h be? 10. Make the height of the slide 1. Calculate t. Calculate your actual dx. Double the height. Calculate your new dx, v final. Calculate your new range. And then divide the first one by the second one to see what the heck happens, what relationship there was. For one of them, you would notice you got a square root of 2. You would have noticed you got an answer of 1.41, which is the square root of 2. Did you follow that okay, Nicole? Okay. That's up there. Virtually cool. By the way, I think that means if I triple the height, I'll be root 3 as far. If I quadruple the height, that's what I need to go twice as far. Okay. Any others? Pardon me? There is one nasty multiple choice question on this particular test. Like this? No. But I've left it on for years. I snag it from a provincial. I'll give you a hint tomorrow. No. It's a multiple choice question. Number 6, I think, but don't quote me on that. I have to remember. But there's also some pretty easy ones. This test, most kids find the written section pretty straightforward. Hey, it's going to be a couple of roller coasters, probably one with heat, one without. It's going to be something similar to what Nicole asked me about number 15. And I think that's it. Hang on. Let me pause the recording. So for those of you at home, I just brought up the test not in front of the students. Nice try. There's four written questions worth, I think, 30 marks. One of the written questions has a part C, using principles of physics right to explain that particular one. I've dropped hints left, right and center, left, right and center, left, right and center. In fact, almost every time I've mentioned a particular love of mine, I've gone off a gentle tangent and tried to hint to that one. There is a second using principles of physics right to explain. This one is the first one that I'm giving you called turkey. I'll give you a gentle hint tomorrow in that what I will do tomorrow is tell you what not to try. I'll say don't use this approach, don't use this approach. Try this approach. The multiple choice, I would argue, is tougher than the written. The written is mostly plug-and-chug. Most common mistakes, kids forget squares and square roots. They forget to do V squared, or when they're finding V, they forget to square root it. Multiple choice, there's seven questions. Number seven is tough. Number seven to me is the third toughest question you'll have all year. It's a multiple choice. Again, I don't mind doing that because, well, when the provincial was around, they did that on the provincial to make a couple of curve balls, but certainly for those you're going on to post-secondary, which is most of you need because most of your academic kids who have always known what the right answer is once in a while, you need to learn what to do if you don't know what to do. And so I'll gently want you in love. You need to make sure you know what's a scalar, what's a vector. I think everything in this unit is a scalar, if you're not sure. Work? Scalar. What about energy? Scalar. What about power? Scalar. What do I measure power in? What? What? Oh, what? It's joules per second, but we gave that a name. It's watts. Also remember we said power, although it's defined as work over time, if I broke work out, it became force times distance over time. It actually became force times velocity that's handy to have, I think on one question you might use that. The one you're going to be using the most on the multiple choice is the work is equal to change in kinetic plus change in potential, which is also equal to force times distance for the area under a ground. You should find if you've done the review, I won't say you won't find any surprises on here because that using principles of physics, it's so this time, I am throwing one at you called turkey. I have to eventually. Everything else though is variations on a theme. Certainly the written section, I guarantee I took questions from the review, changed the diagrams, changed the numbers, but it's the same concept. Hey, I'll even tell you. That is at least one of the good of your roller coaster because I'm nuts about roller coasters. Having given you a bit of an explanation and done a bit of a like this question, are there any more from the review you want me to do? I'm willing to go longer. It's a short unit, so I'm not sure how long this tutorial is going to go. Those of you that come to the log tutorial, that'll last a lot longer. Believe me. Right now it's out of 48. It'll be out of 46. That doesn't mean anything, Joel. The test can be out of 100 or out of 1000. What you really want to know is what's it worth? You may recall at the very beginning of the year, my friend. I gave you on my course outline what everything was worth. It's worth 12% combining energy and momentum. It's actually two unit tests each worth 6%. This first one will be worth 6% and your momentum test will be worth 6%. Basically, two thirds as much as the first two tests. Not worth as much. What's the biggest test? Circular motion and gravitation. Any other questions at all? Sure. Can you let me find the question first? Hang on. 27th. I said efficiency is power out divided by power. Since they gave me watts, what I started out saying, look up, kiddo. Sorry. Oh, screen's frozen. How about that? I started out by saying, since they gave me the power, I want to find out how much power I got out. It's how much I got out divided by how much I got it. How much did I get out? Powers work over time. We're lifting MGH over time and I got 784. That okay? I got that much out. I put that much in times 100. I think when you go 784 divided by 1,000, sorry, divided by 1,500. Let's try that again. 784 divided by 1,500. I get 0.522. That's as a percentage. Here you see a percent symbol next to any of these. So the units are right. They left it as a decimal. We usually mention it as a percentage because how efficient is an object? It's 80% efficient. We don't usually say it's 0.8 efficient. Yeah. Number 37. Kind of close. What did you do? So you said V final is 0. V initial is 13.9. Oh, sorry, from red. V initial is 0. V final is 13.9. And then you went, D is 35. And you found A. And then when you went MA, if you went 925 times A, that also gave you 2550. Look up. You got that. 25 or 2,500. Give me a second here. We know VI. We know VF. We know D. A is going to be VF squared minus VI squared divided by 35. Your acceleration is going to be that times mass. You're multiplying by 925. There's no way. Now, why is that wrong? Did you get the acceleration of 5.52? Is that right? VF squared equals VI squared plus 2AD, right? So A is going to be VF squared minus VI squared all over 2, Mr. Deweyck. 2 times D. You got that for acceleration? You got that? Yeah, that'll get you there, too. I used energies because my mind was thinking that way. And I must have, when I was picking, see the provincial exams used to go by topic. So the first five questions were projectiles and forces. And then the next three questions were energies and the next two questions were momentum. So I picked stuff from the energy section. But we're at a point now we have options. Yeah, that works. In fact, look up. See my mass? Yes. That means that this, this, and this are A. Can you see VF squared D on the bottom and a half? It's the same as having a 2 down there. There is VF squared over 2D. VI squared is zero. So you're actually doing exactly the same numbers as I did. Yeah. Any others? So I'll do about 10, 15 minutes of Q and A at the beginning of each class. What's the block order tomorrow? So block F people. Don't be late. We're lucky to get extra time. It's a Thursday. Iron Mercury day. Iron Mercury day. Right? HG. No, E, F, E, HG. Periodic table. Right? You figure that out? Iron Mercury. F, E, HG. Period. I didn't think of that. I had a really nerdy student a few years ago. Josh Morrell thought of that. I was, oh, I'm using that forever. Pardon me? We've got it for about five years now. Yeah. Yeah, we lost those. The district took those away. Bitter we are. All right. Someone has asked, are there any more questions that I like? Something sort of like number two. Let me see if I can find a better one. Four, definitely. Five. So all variations on number seven with the, I can either ask you the final at the bottom or if I give you the final, I could ask you what initial height was or if I give you the initial height and be final, I could say how much heat was generated. In other words, starting with this, I can ask you anything like anything from here or here or here or here. Right? As long as I give you the other stuff. All variations of that boy. Twenty-two. By the way, not that I like number 29, but boy, if kids got that wrong, to me that's like a freebie marks, right? We don't, I mean, D, grams and minutes. Eight centimeters. See, centimeters? What? I'm looking here. Sort of a variation on number 35. Thirty-eight, no. I solved this with forces. There's probably a way to do it with energies. I haven't been able to find a clean, easy way to do it with energies. So I just did. In fact, thirty-eight, I'm pretty sure I gave you almost identically to this one on your last forces test. You had something sliding up a hill and how far will it move or something. Right? So thirty-nine, I'm not going to give you a component one, although if you were writing the provincial and one did show up, I'd expect you to be able to not freak out and say, oh, I'll just find FX because that's the force in it. I'm not going to give you one like that. I did components last unit, I think. Shannon, the answer to your question, all the other ones that are in my mind, they're half of one question and half of a different one and a combination of this and that there's no blatant, hey, that's exactly what you're going to see on the multiple choices, which is why I said, I think you'll find the multiple choice a little bit tougher. The written, you should find plug-and-chug. In fact, my suggestion next class is probably going to be do the written first, then go back and tackle the multiple choice because the written, you can plow through fairly quickly and know you're going to ace it, most of you. The multiple choice, you can get bogged down. I have one question in my mind in particular that can bog you down. Don't let it bog you down. Any other questions at all? Okay. Nicole, I had one at one point said I would print something out for you or you can, there was that number 18 or whatever you were trying to write it down. You can get it online as well, yeah? Sorry? Oh, you had? Okay. Chairs up, my children.