Okay, so we've got a block draw it here, I'm going to call it M. One and it's going to sit on another block M. Two which sits on a table we've got M. One is five kg. M two is 15 kilograms. Um And then you between the blocks static, is this mu between the blocks kinetic? Is this um Actually that first one should have been a three? Um You with the table static. Is this mu table kinetic? Is this a free body diagram of each block? Naming the forces? Um There's going to be, oh I forgot the force F. Here. Okay. I. M. One. There's going to be the weight gravitational force, there's going to be the normal force and then there's going to be a frictional force that's going to caused that block to move in this direction. Okay. Now in block number two there's going to be uh gravitational force. There's also going to be uh huh. F. G. One from above. There is also going to be a normal force, there's also going to be a frictional force from above and then there's gonna be a frictional force with the table. Okay now I did notice that the answers are in the back of the book, so I see a normal force on one, friction on one and wait on one. Very good 12 I see friction to frictions. Oh I forgot to put the main force, the pushing force, yep. Okay, I've got all of them labeled now. Um Next part of the question is just before it moves at the instant when you've started pushing but we haven't quite started to move yet. So in B F G one is just going to be M one times G F G two is going to be M two times G. So F N one is going to be F. G. One because they oppose each other. F N two is going to be F. G. Two plus F. G. One. She too. Okay, so let's make sure that I get those, putting this in a calculator, M one is five. M. Two is 15. You B. S. Is three. New B. K. Is 0.1. That should have been 0.3. Yeah. Okay. New T. S. Is 0.5. You T K. Is 0.4. Um G is 9.81 Okay, now let's get some of these. M. One G. So F do you want is M. One G. That's 49.1. F. G two is M two G. 1 47. Fn two equals F. G. One. Yes. F G two 1 96. So let's make sure that I got these right. 49.11 47. 1 96. 1 96. 49.11 47. Okay, very good. I've got the vertical ones correct Now, horizontal ones. F. F B looks easy. Is just going to be force of friction. Yeah, in the B direction. Hm. Well that's going to equal M one times a one. Let me look at the question again. If no motion has started, if M one is not accelerating at all, then FFB would have to be zero because it equals M. One times acceleration F F t would have to oppose F. So F F t minus F would have to be zero. So F would be F F. T. Which would be um U sub s mm times times the normal force on two, but the normal force on two is fN two. F. N two. Okay. Um And this would be F with the table S or mute table S. So F is going to equal mu Abel S Times F. And two. Just 98.1. So this is part B. And in part B. I do see the 98.1. That's good. But it's showing me that there is a friction force above which is 14.7. So it's showing a friction force here here. Why isn't it drawing here of 14.7. So if nothing's moving if the lower block has not even moved. Well let's just see mu sub S. Musa bs times the normal force times F. And one. So I guess that still makes sense. So musa bs times F. N. One. Where am I? So F F B equals you? B. S. Mhm. Times F. N. One. Okay but didn't I get FN one already? Oh F N one equals F. G. One. So I didn't declare that yet, there's the 14.7. Okay, so that makes sense that even when it's not moving, there's still some friction there. Okay. See with the acceleration for each block, what's the acceleration for each block? And why? And be does is there an answer of 113 Newton's in the back of the book? Let's look at B again. Yeah, I don't know why in part B there's an answer of 113 Newton's that seems, I think it's not answering anything. So let's go to uh see so now everything is moving. So um if everything is moving then uh F the some of the forces on yeah. Block one, which is F F. B. Has to equal mass times acceleration. So that FFB would have to equal M. One A. One. So A is gonna be F F. B over round one. See what that kiss me A one equals F F B over M one. Okay, but when everything is moving then this would have to change two kinetic friction. So F F B would now be um you B k f N one, New b k F and one which is the same as F G one to That would be correct for the motion of B because now it's kinetic. Okay, so acceleration of block one is 0.981 meters per second squared. New kinetic um over times F N one for M one. Okay. 0.981 meters per second squared. Okay, so now I need to get the acceleration of M two. So that would be f minus F F b minus F f T f minus F F B. Yeah, T is going to equal M two times A. This is a one. This is a two, so a two is going to be f minus f f B minus f F t over em too. Okay, and everything is kinetic, so just to make sure that I get this right, I'm gonna basically redo the calculations um F I do have minus F F B I have right above it, which is gonna be new. BK I'm F G one Okay, times F F T. But F F T was mu t k times FN two. Mhm. Okay. No, I want to divide by M two. What are the chances that it would be the exact same thing? Yeah. Yeah. Okay and I was thinking about it and this does make sense but the acceleration one is going to be relative to acceleration too, so a one is really going to be this plus a to all of this, erase, oops, trying to erase probably an easier way to do this. Um Plus a two plus eight to because it's going to be relative to +82 And so that's going to give us the 0.981 here. But it's gonna give us going back to the calculator here. Plus a to whoops two 1.96 here. Mhm. All right, so thank you for watching.