 Okay, first of all, really quickly, if you go PhysicsPitMath.com, Physics12 links, and then at the bottom of the very first page it says, click here for some tutorial videos. I do have last year's momentum tutorial online as well. A lot of it will be repetitive, but looking for a second explanation of the same stuff and I might do some or cover some details that I haven't covered here. Without any questions from the review that you want me to do, now is your chance to ask. So hearing none, let's talk about key questions. What do I expect you to do? I won't do stuff from the review here then. I'm just going to make one up. I'm going to do a lousy drawing tutorials. Here, Mr. Dewey, let's get clever. Right click, copy, tutorials. Physics12, hey, momentum, this looks pretty good. That's from the review. Oh, I know what I did, Mr. Dewey. This was really clever. Copy, this is what I did for the tutorial. You forget your new stuff sometimes, get an old face. What I would expect you to be able to handle is a question like this, but smaller and on the screen. So here's an example. A 27 kilogram object moving eastward, you know, as soon as they give me a compass direction, and again, you can write this down if you want to or I'll print this up when we're done at the end, whichever way you learn best. A 27 kilogram object moving eastward at 17 meters per second exploded into a 17 kilogram fragment and a smaller 10 kilogram fragment. After the explosion, the 10 kilogram fragment moved at 18 meters per second, 33 degrees north of east. The speed of the 17 kilogram fragment after the explosion. Is there a collision? No. Is there an explosion? Yeah. Momentum. Let me get rid of this, too. The sum of all the initial momentum has to equal the sum of all the final momentum. Is this question looking like it's going to be in a nice straight line? I can let to the right be positive and to the left be negative. Or is this one looking like it's going to have angles and I'm going to be doing doping and cosine law and trig and stuff. Angles. So I'm going to raise my gang and get a little more paranoid. I'm going to say, okay, before the collision, oh, it was the whole mass that was moving to the east. I have this. And its momentum was mass times velocity, which is what? Don't I'll rush for your calculators at once. 675? Double check me. Yeah? By the way, quick review, what are the units for momentum? 675, what? Yeah. They haven't shortened that one yet, kilogram meters per second. And then, so before there's that much, the momentum has to be that. After the momentum has to be 675 kilogram meters per second, do east as well. But it explodes. It explodes into north of east. Here's east. There's north of east. And its mass is 10, and its velocity is 18. It's 130 at a 33 degree angle, plus, I don't know, is that okay? Now, I'm pretty sure that if part of the mass went upwards north, I'm pretty sure a picture of the second momentum would look like that. The other reason I know Shannon is if I add that plus that tip to tail, that's the only way I can get a horizontal line, which is what we started from. I know it couldn't be pointing up that way because there's no way I could add those two tip to tail. I kind of just reasoned my way and I said, look, if I want to add these two to get what I started from, if I'm going up, I better also be going down. Did I lose you or is that okay? So let's draw this triangle. That's going to be 180, mystery momentum, 675, and that there is 33 degrees from there. How can I find out how big this is? Cosine law. Sorry, no so katoa here. Momentum two final squared equals 180 squared plus 675 squared plus, Mr. Duick, no, minus two times 180 times 675 cosine 33. Joel, do you have to memorize the cosine law? Why? It's on your formula sheet. You just have to know how to use it, what goes where. Who's in math 12? Degrees, not radians now, please, and what is the answer here? Can you print this? Let's see. Mode. I'm in radians now. 180 squared plus 675 squared minus two times 180 times 675 cos 33, oh, square root. Do you have a final momentum of object two of 533.13? Final momentum of object two equals 533.13. Now that's not what this question wanted. This question wanted me to find what was the what. Now the nice thing is it didn't say velocity because I don't have to do trig to find direction as well. It just wants the speed. If I know the momentum, how can I find the speed divided by the mass? The speed of object two is going to be 533.13 and I think object two has the mass of how many kilograms divided by 17, 31.4 meters per second, 31 meters per second. That says a multiple choice question. I would have no problem giving you this as a written question, but then I would say find the velocity. I would then say to you, all right, direction. Now this one is a yucky direction. This one's direction would actually come from right there. It would be south of east. It would be that angle. The problem is that angle is not in my triangle. Oh, but I think it's the same size. See the Zed? I'd find that angle, but I would write south of east. I don't think I'll give you one like that on your test. It'll be a cleaner angle to find, but there it is. Is that okay? Now Ashley, this was an explosion except this was a bit different from some of the other explosions we did. I think all the other explosions that we did had an initial momentum of zero because it was at rest and it broke into three pieces. Here I had an initial momentum that wasn't zero. I broke into two pieces, which still gave me one, two, three vectors for my triangle. Here's a much more common written kind of a question. Eric, can you see just by glancing at the diagram, this is going to be angles and trig and such, okay? Is there a collision? Yep. Do they stick together or not? What's the fancy word for bouncing off of each other? Elastic. Fancy word for sticking together in the elastic. Yes, I know they're very close to each other, but such is life. Can you guys handle a question like this? Zae's nodding, Eric's nodding. I'll do it if I need to, but if you guys are okay, we can move on to other stuff. And you okay? It would be, I'll start it and then I'll let you take it the rest of the way if you want to. Joel, I would definitely start out by going the sum of all the initial momentum equals the sum of all the final momentum. I would say the initial momentum is 1.5, 15, Mr. Duk? Nice track, 1.5 times 72, whatever that is, equals. Then I have this way, 43 degrees, and I have 1.5 times 43 plus that way. How do I add these two vectors together? Draw of M. Now this is a bit of a wonky diagram. Can someone go 1.5 times 43 on their calculator for me? Should be 43 plus half of 43, should be 64.5? Sorry, what? How about 55 degrees? Thank you. What is 1.5 times 43, though? 64.5? Well, I would go like this, 64.5. And then I guess this vector has got to look something like that, because I know it has to add to whatever 1.5 times 72 is. That's going to be 108, that's my diagram. So this angle is 55 degrees, doesn't help me. What's that angle? 125, and then away I can go. That's a tricky-ish diagram, because it's all slanty, but I would still consider that fair game. That's the same kind of question. What direction? That's the same kind of question. Those are angular collisions. What about linear collisions? Let's look at some of the ones from the homework. So let's see, here's example two. What kind of a collision is this? Angles? Nope, nice straight line. I do see the word rebounds, yes. I better let one velocity in one direction be positive, and the rebound velocity be negative. Or you could let the rebound be positive, and the initial be negative. It doesn't matter. You'll get the same answer no matter what, just be consistent. But this question is actually asking me to find what, Trevor? Number two, how much what? Kinetic, I gotta be fussy. No energy is lost. No energy is lost if we're talking about any types of energy, because energy is conserved. But how much kinetic energy is lost? Let's go see. Momentum answers. There is still a collision, so I'm going to start out using momentums. Momentum. Assuming my document decides to load here, bear with me. Well, I'm like, I'll figure things out. This doesn't build well. Not responding. Yeah, I got that. That took a while. So I still use momentum. I let the initial be positive, and then the rebound be negative. And they told me it's in a nice straight line. So I get a nice linear equation. That times that equals that times that negative, plus that times that. I solve for B2. Except the total kinetic energy then, Trevor, now energy is a scalar. How much energy was there before the collision? Only one ass was moving. So it's a half M1, B1 initial squared. How much energy was there after the collision? The first mass is moving, the second mass is moving, and I don't care about negative or positive. Energy is a scalar. After the collision, there was 205.5 joules of kinetic energy. How much was lost? 24 joules. Where did it go? Heat, sound, distorting whatever the collision was. Distorting the surfaces. So there's an example of a straight line one. Number four is talking about change in momentum. What's another word that can be used interchangeably with change in momentum? Sorry, what? Say that again? Get impulse. If I say what's the impulse, what I'm really saying is change in momentum. And what's change in anything? Say final minus initial. Oh, the odds are somewhere on your test, I'm going to say find the impulse. And what I'm really saying is find the final momentum, minus additional momentum. Now, it'll almost certainly be a straight line. What if it was finding the impulse for an angular one? How do I subtract two vectors? I don't. What do I do instead? Flip the second one and add it. So if the second one is pointing east, make it west. I've rarely seen that come up. If it did, it would be a nice right angle one anyways. I think I might stick one in somewhere. Number five, so here's an example of a nice straight line one. Is there an explosion? So for part A, when it wants me to find the speed, how much momentum before? Boom, it has to be the same amount of momentum afterwards. And then what's the impulse given to the probe? Now, the probe is just part of this. Its initial momentum would be 1,500 times that. Its final would be 1,500 times 140, final minus initial. There's your magnitude of your impulse. Since I specifically said the probe, I couldn't look at the whole spacecraft. I'd have to look at the individual masses. Define impulse change in momentum. Explain why the impulse on the probe is equal in magnitude to the impulse on the capsule. Whatever momentum that the probe gained or lost, it's the same amount that the capsule lost or gained because momentum is conserved. Impulse is measured in which units? Number six, what I measure impulse in? Two ways. Since it's change in momentum, it is kilogram meters per second. But impulse was also equal to what times what on your formula sheet? Yeah, force times time. So Newton's second, D. Let's find a good written question. So you guys are OK on the angular ones? Here, another angular one, except the masses stick together. OK. Oh, a little twist in number 16. They're asking you to find the mass of object M2. Really quickly. So I started out the same way. And then apparently the W and exclamation mark vanished. I had to rewrite it. This one was a little bit different in that I ended up using the sine law because I knew two of the angles. They gave me two angles in the question. And since I knew two angles, I had a pair. And I was able to cross, multiply, and solve for M2. I don't think I'm going to give you one quite like that on the test, but it's certainly fair game on a final exam or a provincial exam or something like that. I like number 19. So hopefully you've clued in. I like the angle one. So like number 14. I like number 14. I like number 14. I like number 14. I like number 14. I like something like number 19, where there is a collision and energy, a change in height. Something like number 22, an explosion. Although the explosion that I'm going to give you is actually breaking into three pieces, I think, where your initial is 0. So I think we have one like that somewhere else on here. Something like number 24. There's definitely going to be a rebounding question or a bouncing quest or something like that. Or it's linear, but the change in direction you have to recognize is going to be negative. You're going to be bouncing off of a wall. Or another easy one is simply this, bouncing off the ground. Works great. Brett, you going to make it? You're not looking good. 30 also. Hey, collision and a change in height energy. Yay. 34, 35. Again, a collision and a change in momentum and a change in energy. Yay. By the way, 40. The only reason I included this was the fact that they move off at right angles. Makes this question nice. It says 52 AMU. Who's in chem? What does AMU stand for? Stands for atomic mass units. You know what? Mathematically, it'll work just fine if you treat that as kilograms, as long as you continue all the way through. So let your mass be 52. It's an identical nucleus. Now, the fact that they're at right angles and the masses are identical and it's so bleak, there is a shortcut. This is that weird, obscure, perfectly elastic collision, which was the third type of collision that I mentioned that was like a subset. You can do this. There's a shorter way to do this. It'll work fine with momentum. I mean, that's really this unit. Did you have any questions at all from the review? Yeah. Go ahead. The one you have to write out using the physics. Like, are using principles of physics right to explain? Can I go over one from here, or you want to hint at? I'm not going to give you a hint about which one I'm going to ask. I think, let me see which ones are on here. Well, we talked about how crumple zones work. In fact, I use the full NerfBat instead of crumple zones and I hit somebody upside the head, did I not? Here, increases time, which means the change in momentum is the same, but it's also equal to F delta T. If T gets bigger, F gets smaller, that's good. Here, same height. Why? Masses cancel when you do energy. Oh, sorry, not masses cancel. In this case, change in height, new slope is different. Energy is a scalar. It doesn't matter whether the slope is that steep or really steep. They're still going to get to the same height. That's the nice thing about energy being a scalar, as long as your slope is frictionless, which this question mentioned. That's more of an energy question though, so that belonged on the previous test. Defined input, we talked about that one already. Two gliders having equal masses, approach head-on. They stick together and remain stationary. Does this mean momentum has been lost? No, if your final momentum was zero, what was your initial momentum have to be? Oh, in fact, we started out looking at the head-on collision between a big semi-truck and a little tiny car. We noticed, yeah, the momentum was zero, but momentum is a vector. I would say, if you're wondering, I think for using principles of physics type of a question, one of the key ideas is momentum is a vector, not a scalar, which means direction matters and makes it different. That would be something I'd probably want to emphasize. Certainly, if there's a change in direction. Then I'm going to pause the video. In my usual way, questions that I like from lesson eight, which was the last momentum lesson. It was this one here called Explosions and Other Problems. I like example four. I like example four. I like example four. And I like example five, which suddenly I've lost. What the heck happened here just now? There's example four. Okay, example five. I've suddenly lost the writing four. Let me change documents. Something bizarre glitch just happened. Example four, I like example five. For you guys, was a roller coaster, was it not? Yes? Rolling down a hill, colliding in an up a hill? Can you find? Mine just banished suddenly. It was right there 30 seconds ago. You have it on yours? Lesson eight, the last lesson. I like example four and five. I think you'll find the written very straightforward. Couple of curve balls on the multiple choice, but nothing so crazy nasty as the one number seven from the work energy test, okay? I would probably do the written first and then with a way at the multiple choice because the written is pretty plug and chug.