Now, I'm going to demonstrate conservation of momentum, but you need two bodies to demonstrate that. So I'm going to bring in undergraduate, Cena. Hello, world. Okay. Cena should be studying English lit or some lesser subject right now, but I asked him and he agreed to come do this demo with me. I was actually bullied into doing this, for the record. No. No. No. This is total voluntary. So what we're going to do is we're going to be on our little carts here and Cena will be here, all happy undergraduate and I will be here. I've seen some stuff. I've been through it. So neither one of us are going to be moving, zero velocity, so our momentum is zero. My momentum is zero, his momentum is zero, the total momentum is zero. Then we're going to push off of each other and see what happens. So let's find these up here, and this. Get back on yours, and 3, 2, 1. All right. So after we pushed, we both started moving, right? We've got a velocity. So Cena is going this way with what we'll call V_Cena, and I am going this way with what we'll call V_Jay, V for Jason. Now, it looks like we've created momentum. It looks like we've forgot to conserve momentum. How do we explain this, Cena? Well, momentum actually acts like a vectors you see by the arrows on top of the labels, so it doesn't act like a scaler. So MV_Jason plus MV_Cena must be zero. But right, since they're opposite directions, if you did it in 1D, you would think of 1 is negative. You could say minus M, the magnitude of my velocity. If I call me the negative direction plus the magnitude of Cena's velocity. If you call him the positive direction, would be equal to zero. Yeah, so it's because momentum adds as a vector, right? What did I do? I left off my notation exactly and Cena the needs that because he's about to tell us, calculate for us, it looks like we're going about the same speed. But should we go the same speed? What speed should we both be going here? Let's see how much freshmen physics I remember. So on this other side, we have as for Jason. Right. Cena, so you should have been going, how fast? Solve for you. Cena, M_J, right. So his velocity should have been a factor of the ratio of our masses more than my velocity. So now, we get a little bit personal. The ratio of our masses. I don't know if you want to get into this, or whisper how much you weight right now? Thirty eight. Yeah. Okay. Yeah a little bit more, a little more. So this factor here is about 1.15. So we'd say that my velocity with a cursive J, they don't teach cursive anymore, his velocity would be 1.15 times my velocity, like that. So that's not a huge noticeable difference. If you watch closely, you might be able to tell that he was recoiling faster than I was. So what I'm going to do is, I'm going to gain 30 pounds real quick. Now, one way would be where should we go eat real quick? Whataburger. Okay. Camera guy can stay. We'll go to Whataburger. No, let's not do that. What I'll do is, I'll throw on 30 kilos of weight onto my cart. So let's re-setup. Burger. Now with an extra 30 kilos, that ratio should go up quite a bit. Hopefully, you'll be able to see this scene, it doesn't need move quite a bit faster. I'm also going to push them really hard. So that will also help us see. No, I can't get sideways. Here we go. Let's re-align it up. Three, two, one, there you go. He went much faster than I do.