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Basic Physics Lecture 22

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So let's go ahead and get started Our sigh quiver like Friday crown erode day ready for Memorial Day today a little different hopefully got the e-mail I can't decided this last minute obviously decided yesterday The organ of a basically Have an exciting day today solving 2 problems Drive End There are 1st What I would call real examples of how the Triborough problems it certainly would be on the final on that even with This next midterm coming out on the free response energy problems will almost definitely involved some kinematics force or momentum Adobe a multi stepped problem so given the complexity these you may have noticed I posted a 70 e-mail fill in the blank buyback solutions that you could not and have you today to go through and villainous lecture us because As I go through these Iowa who spend a lot of time even more than usual pointing out how to think about a problem like this how to approach Carter recognize what you're doing and and a little less time actually solving the details so you really wanna go look at the solution when it gets posted after class but If you have that fire bikes thing in front of you as I discussed the different things that cannot be set up better go hearing in a kind of can help you formulate thing so hopefully that I help you out Sound Not much else said the beginning Celestia's get indirect what I will do I'm going to give away the answer to 2 of the 4 clear questions right now so render the 1st problem which will involve using our force laws less energy and we're going to do a 2nd problem
That involves energy and kinematics and I'm telling you this right at the beginning not just to give away as clear question but also so be prepared To watch for that list it see how I recognize that that's what's going on so let's go 1st problem This is a bouncing on a trampoline and This is 1 thing you have to watch for now that we've learned about Springs there are lots of things in the world that act like a spring you saw organ a review it E-mail makeup that homework 7 . 9 problem was a bit of a challenge the climber falling with the rope and the rope stretching the role with sprained extracts had a spring constant that when you'll see is actually much easier to visualize understand with energy conservation and we did that in the work chapter you should have used work done by gravity work done by spraying if you go back and do it I'm pretty much if trampoline problem and said I'm about to do a do energy conservation you'll see it's much easier but We have to be repaired or is it me track like this ring that means better basis before slot that people's minds kayak and it has a potential energy of it and the system of one-half square and so the key thing is always the spring constant Ogata spraying I've gotta worry about Now this actually to pieces of information just and still on the trampoline that displays a certain amount from its equilibrium ones you know something as a sprained it will have an equilibrium position in case the trampoline in case you were not familiar with them that the trampling slap so I can draw on this would be a miracle at Y Y equals 0 the equilibrium position and then when I stand on it The trampoline looks like and displaced White post . 2 meters down says the 1st thing I learned in this problem now When I jog on tripling the 2nd thing that I'm doing I'm told by go down 1 . 5 meters and I finally get the question how high above the flat trampoline do I get what I'm bouncing like that So do we aren't get the situation this is the actual question so Nasser fine It is basically a bar fight Above the flat trampoline or any crisis and the problem Fed Mr. 1st clicker questions While using cinematic forces energy but they didn't see 4th both B C 34 per cent and The 1st we are going to be using forces an energy so let's spend a moment kind of taking us apart The tumor oceans there were dead were given a situation right that involves a single instance we are stale Ever our emotions that changing so the 1st thing we know were standing still Now sometimes velocity to be 0 and changing or just standing still on the trampoline and nothing's Abbott hanging out what we know about our most motion what big physics thing immediately Yeah you know my gravity something else something about object whose velocity is not changing shattered altogether now Accelerated 0 You need to know that these are the sort of thing is this is this is the heart of What causes the most problems in physics recognizing these things his way more valuable than asking yourself when you start what equation should use your right to what equations it almost never get that right if you don't know what the motion is 1st be able recognized when you have Accelerated was 0 when you have a given price acceleration or when it moving in a circle so you have centripetal acceleration Emelita you in poor and stuff about the situation we merely No 8 0 0 and we know or at a single incident that means there was no additional flying all right a key figure about energy work energy was always about the difference between the initial and final Once you see these pieces always concept from the course that really available to you it is ethical If you want a large any now you may not need to learn anything about this situation I might have just told you about this for 5 but if you're going to use this part of the problem the only chance at that could be connected to it is that we've learned as a secular because A single incident while you're standing there and Lobbying 0 acceleration connected Maddox's about moving from 1 place to gather energies about it before and after it was see momentum conservation about a before and after work has it dealt to act on impulse our next week of the delta T so this is a big The the recognized a right away Not even deal with the question and the answer digital recognize OK that a part of my problem but I need use part me is that it was a main somewhere and and file that away from me right now the questionnaires about how high you're going right and it's got an initial state where you're stretched down and a final state where you're up some height h final now moving from some position of flying through the air disarm height what are the possible ways you might find heights when you're thrown up in the air was actually too To We we learned to read plants and so far they on mobile tries to Maddox forces and conservation of energy or work and the more general 1 of our every concept Where he was managing kinematics enforces which Would allow you The salt for difference some initial conditions what final height you get Possibly
Energy use early do that in principle because about before and after I what do it to demand that the 1st weaker segued comedy brought throwing 7 of their last went right now why in this problem is dramatic and be very hard to use what we kind added here that makes it interesting This whole business with this rank right I kinematics problem is always about You know really not Then you couldn't find a right that in a match showing you back here were starting somewhere were given generator V not only leave the trampoline but we all this initial stuff so that's where we really immediately go that's better start with energy we might find As you start to set up a problem but you actually used 3 ideas might be be a problem really need use energy did at the beginning part in kinematics later now it's not the whole thing with energy but there are times where you might end up losing all 3 of its Moeller Plaza any questions about how I kind of attack this and broke in these pieces because that when you're faced his problems if they don't take toured every minute 5 Missouri inning to break down what are the motions of dealing with What are the most likely physics and dealing with it's really really hard to make progress on these images trying sample from the beginning that Equations yes A diplomatic what I did was Let's apologies on assault right what 1st white things I need constant acceleration and my equations Raul about dealt the X it was something and we finally people something and they all have been ordered and right thereby look over here The MIB here is 0 I can ever be be because of the right not to matter was all about being once in the air and only having gravity and for this whole motion here I have a spray and the big thing about the spraying writers every gold miners kayaks not constant Acceleration deceleration changes because the spring force changes before saying a changes so one-third from that brings us rating is a good and you're either use forces energy regular can eliminate kinematics for that part of the problem now will see in our next problem we have a spring larger to something in the 2nd half we used to that so you could have ended up having to use it here but because we're going in a straight line we know of emotion But Australian all we care about is a final height were pretty common and hikers G-8 we should be over yet so that our rooms start with energy but it doesn't give us enough yet replica something else but we want a start there any other questions requested path so let's started having decided that really use energy songwriter redraw things so for the motion I've got my sprained coming down and they did 2 things and this is a one-time you're allowed to do this on gonna call this a cheap 0 0 0 For the gravity part of the problem but I'm letter called x equals 0 for this rank and you'll see why I'm am allowed to do that and I'm that somehow 8 8 that's where I and that way read the problem the answer I actually want is 8th relative The flat point of the spring so I did a lot of different things here I could put a 0 Right here if I wanted and that I have a negative light but I'll find it easier to put it right at the bottom of where I wanted beat out because emotions wording decided to use energy so I must figure system so let's go back Through our PowerPoint slides Bend forward I didn't have a warrant for a system OK let's The car system and then ask that question right I'm going to do The trampling reporter said and the earth Pretty much everything A nice thing for this I know the net Forest is 0 so now I know there's nowhere so I'm actually use Dean conservation of energy I don't have to His work equals change but basically the same thing but it's nice to be specific to look at all by solutions while ago strategies and you'll see that so now Which type of energy used to read having bad system Talk to the person next to you and determine which type of energy unit Bob let's see what with his at least 2 of them and so you might as well go with that right there no friction and this problem right and this 1 here Was big that I have to do it Are energy dissipated with his or force of freak and existence but there's no friction here so I don't have to A worry about that what I do have both the spring in gravity because I'm the earth in the system this happens with the earth there if I did not I would have worked on by gravity because I'd have a force on the system likewise I put the trampoline which in this case Is arse ranked so it has its energy Having said that Let's make art table of energies what I want you to do is because I think I gave him my little prehend out thing you what is my initial Kinetic energy in this case is really is your letter writer friend NJ 0 Final today and energy 0 wife What is the number 1 reason going back to the beginning of the quarter That Speed is 0 Any final situation Were at the top of our job and that's what and that is the key about how high I jump that means I'm at the top and so we all learned recall that the speed of the direct your movie role in moving vertically here is 0 so That is nowhere did it saying that it was 0 right As I put out For Carey and at
Each there we hope There is a store and if for Remarks from only talk to neighbor Oh and were back What is a yacht the rail
While there was I thought of my head so that I haven't had any Technical difficulties yet and I forgot the knock on wood and sure enough PowerPoint hangs now Were backed by potential energy from the spraying once our national potential and gibberish sprang 1 after its work and not as wide as acts It's are 1 . 5 meters there were down and not ax career so For potential energy doesn't matter whether I call this negative 1 . 5 or Plaza 1 . 5 the square what might Final potential energy the 0 White who trembling rafters rain back a flat now known as in this case what I've done what my potential energy of gravity initially 0 and what my final Out Gravity and G-8 at this age here as defined by pitcher to rewrite terrible let me know how rare Bozo defying so now I set my initial energy people the my final energy We recall by workers Iran And I'm very happy Ivan expression for the height now and if you like I was dividend problem I know X right x equaled 1 . 5 meters I always know that's my 10 meters per 2nd squared and might Mass was 80 kilograms of my only issue because I don't know at this point because another 10 minutes and the exam I panic but I may also remember what I did the beginning what I said to myself when I 1st look at the words of this problem is there another part of the problem yes there was force for no less What I said on Monday was lecture energy Only chance to give us 1 equation most interesting problems there is at least 2 1 now and there's to announce who were often connected to some other part of the problem so in this case the other part of the problem that were connected to the right Was That in this show a equals 0 Anamoose which so why why was 0 . 2 meters better call that's why Equals 0 and I'm gonna make positive in the other direction so now is the pieces it came in Right I decided I will use every there may so they do identified a buying must have a coordinate system and now was the next thing I will do it Do have forced problem I Drop my freebie was Freebie diagram for me when I'm sitting out there trembling hands down at the bottom But what down Set my way down And what forces out on me We could call it now murderers things right and the old beginning medical the normal forest standard dribbling call it the force the trampoline but my trampoline It is acting like a spring so I got a call at my spring force just to remind me that I have a formula for minors KY notice here is 1 of the dangers when an object acts like this Can I draw and don't do this if I'd also normal forests that Ron there There's just this 1 force between me and the trembling and that you remember write new in-store block tells you that for every 2 others as 1 one-fourth between us so when I was there the trampoline there was 1 the trampoline on me That Forest is given in this case I would normally problem of course But it's given by the fact that I'm treating it as a sprained sewing now formula for it and my wife now I know it has to be up was the spring wind down noticed Minus Y works perfectly because I'm actually at White was negative point 2 meters So when I like that and I have time 0 . 2 meters Which will be a positive number Which is up so you have to be you might decide you don't end up with the wrong number than any does or depth in this case be obvious because You would end up with something that makes no sense we have to forces that add 0 so they have to cancel so I'm writing down there is a lot I wouldn't mind SKY minus and Angie people 0 so soap Can equals energy over Negative why am I plug that then I get 4 thousand new Premier and as I do get a positive number because of this effect plugging in White was minus 0 . 2 meters by getting a negative number for can I did something wrong with my mind sign because kids always positive Any cost gap What But this I put my mind right here Realize When when I write gravity right here and is writing its magnitude at this that's what I want to do this particular problem I could have But depends on how you wanna say this arrow lets me know in this case to direction the matter what playing its help will be very careful Remember that the formula The Has the minus sign in that and actually I should be I should leave my arrow here because I'm really not doing the magnitude of the force spring at this moment in case the direction Ron from being very careful leaving that minus sign here I'm keeping careful track of what y years of all that I yes I got a positive it is up I did it right with gravity The man vases and didn't always down and get on with the minus sign it until I write it was made because that's way I done at all quarters as well do it because I go bad luck which way was positive and I have my showing me down I know this could be very confusing and that but it is it's a fairly common convention and the books and among myself instances when all the rest of my lectures turned it down positive Right That I still would have done to Things and now I would apply didn't over here a positive point to it I would have minus J climbs positive point to class Energy equals 0 So this is for down positive and noticed this still gives me that Which Serbia's I mean side e-mail that formula There's still give me that answer because from here I still have a People's Energy over 0 . 2 but is that But It is a best because I do mix 2 different things the magnitude or the non-bank yes Because that is where I picked age to be 0 at the beginning And remember we said the other day All that really matters is the change of potential energy so where Potential energy 0 It is arbitrary You're freedom and not I'm freedom spraying was The 1 place We don't need this Important system for both potential energies because their changes but not add Values and their they're done separately so I can do my potential energies for my spraying with a different court system But I do my potential energies for gravity and that's what I did noticed right For this Frank 0 is here for gravity 0 is here and that also is very common view read all other solutions when I posed the you'll see the butt doing that now sometimes they pig 0 the same everywhere they get negatives for potential for gravity negative positive I. I always like to make it you go 0 At the lowest point and deal with whether were find a whichever is lower so that never had to do with anything negative but is Yes on the OIC Iike I didn't I just 30 I stepped to do it 2 majors do it right that the more you do these problems you realize up
There's 2 forces So OK why has people energy And that's a magnitude And mileage oysters for Katie over the magnitude of white and undone but If you haven't done a lot of things we don't see that If you do it step by step as every force problem lived that there and that's true of most of what we do now as you've done more of these particularly with the new laws once how are ya right FW and then right at Ng later not just a writer You're comfortable with it Now you're strategy use definition all wonder were MG came from But that's the beauty of having a strategy the beauty of using words and that's another point I wanna make The strategy that is not there for some arbitrary reason the strategy is there so I know you could explain to me what you get And a require Adjusted short sentences about later strategies should master calculation don't have time to do a calculation you write a correct strategy I still know you know do the problem Right You tell me I will use these definitions and those expressions to show up on that Right I need to do do Each that you tell me you're using sewerage musical 0 leaders right was Angie I know where that came from an unhappy so that that's the advantage of it and that's why they go together and we're not sure And you do all this At that point Other questions Yes I have Right so right here Why is the vector cases a positive can't We are saying is that Putting it all together That's right here will be the final in some versions And they'll be movies like that Drive to the real idea As you plan for the final ideally you should be overdue That problem in half an hour that I'm just giving you a Drake that's Any other questions on that Excellent were really do now Instead of a stretch for 2 seconds and sit back down Or stay in your seat strapped or talk to the birds that I have at end you what services waking you up banks are now are always ordered builder a rocket launcher so building a spring-loaded rocket launcher And we're going to rewire 1 there were once As things at 30 degrees Where lodges 30 degrees that travel a 100 meters sorrow and am we compressor spring 5 centimeters We need to know what spring divided that that That a rocket launcher and we know the mass of the rocket were larger so the obvious question what type of physics is to solve this problem can't raise energy kinematics Newton's laws both a and B or all of the above review strongly field It's just a and C bigger nozzle vote for all of the above and tell family later Bachelor 64 retiree remember that we do not need any of those lost this problem So this is why were we just did conservation of energy and kinematics trickier let's to say where that happens now back to the 4th what I would do is right here we are told of flying can now very 1st thing you know we're till the finest cousins realized that I wanted to wait you could do that at was minus kayaks which is using new and or potential energy ranked as 1 have their story which is energy was the only 2 places case shows up we need to do 1 of these now to use millions lot we need no adding and we need to know something about a single incident and the free body diagram up when I rocket are little thing is sitting on the swings and it's been interest 5 centimeters and at that that angle of 30 degrees west the free body diagram for rocket Drive free but a diary that has rocked by Tadesse that on a test Let's make it a little easier just so you You you have your You're rocket launcher does have a low a rocket to be sitting on maybe 2 2 maybe to ramp Oregon and this is the List ranges at x equal 0 when it's the end of the ramp says like a platform muncher Day how many forces do we have at our free body diagram was B 1 B would be to see would be 380 do would be for me would be greater than for go-ahead about You go I am 1 They Tecmar seconds to should Aurora Drive everybody ramp 5 4 3 2 1 I Pretty have you have 4 3 so will start with that is the next biggest as formal see what we at so The three-day you have tell me where they are so yet this Ray Best Bush not wait coming down 103 got normal force They're what else to do we have I forgot to mention it's a frictionless rocket launcher polyester are we die now There are now white he so why Ecuador's breaking the components someone forces And use every goes minus J X defined what I might missing There's a our work as a rocket launcher and was really no either force in my problem when should be happening right now at this instead it's accelerating Eds wanted it to me at rest events at rest this free body diagram is ever going to launch a mere dead only Isuzu over the rest of his 0 acceleration It's never the velocity of that rest 0 accelerated in avalanches joked 2 Hallwood before launching rats that this amount a row rocket launcher Has another force that is even imminent the problem holding complies with those of Drury value but when we let go that launches so that is why in this problem despite the fact that I wasn't telling you explicitly you should be able the recognized I can use was made because I do not know where I don't know what acceleration At the moment when it's compress the subtle but important point and this is the sort of thing that does make these problems occasionally heart now you might have done everything we do is dead and then realized started writing down the reminders that some miners and signed data People's and a again that energy I know and I know the Senator but I don't know and I will go back to a problem that you read the fight have led nowhere defined it You have to rejoice at this point in of problem say Oh while answering to try and find a four-user out this must not be the way it ended problem and luckily lately but although 1 otherwise you really have a so that much time you really haven't you may be spread by administrators provided I Ray writing that down and now you move on that 1 of the things that makes hard and easy you may not know right away what the right way to do it as but there's very few ways to do it If you do it wrong move on quickly another warned that the main point I want to make with this problem but now having made that main point let's move on
Chuck In this problem We have a larger Sitting here from said 0 . 0 5 centimeters And what we now website meters thank you We know we have some spring kinetic energy there were defined cat a ramp equate it to other energies and at this point we realize there may be some potential gravity there may be some kinetic energy will come back for carefully I realized a big thing will be missing is the speed of leaves were Bowie of the center part of the problem and said the problem talked about the fact that it needs to be able a travel 100 meters right At a rival Lee not 30 degrees and I know of them go 100 meters What type of visited my during cinematic back in this problem you'll see that we had a lot careful make their point of 5 centimeters is very very smart very go 100 meters I should've America was at an Atlanta 100 meters at the same height at which it was watched right or you might worry about that little bit of I'd different you that wouldn't come is a big number But You know I might say a 100 meters and land on top of Walton meters 5 there could be other ways of your work We're a wall 5 meters high 80 meters away with other ways of this problem before but now I know I have an energy for here Anarchism export here over the energy I do my usual thing but I always do with energy I picked my sister And in this case on APEC the spraying the rocket or the mass and the earth and for our final quicker questioned what types of energy do we now consider
It is is very similar to be otherwise Those of us After By more segments Aaron were done excellent And it's all but see there's no friction again now artists Sunday moving about as you're studying for the exam so I could have a rocket launcher that has a lot to theirs
A 40 enforce of friction acted on the rocket as it leaves the 2 pretty easy for you that end after this point might want to consider what at the various problems from today's lecture and where are and how good fortune show what Interesting question so anyway I've got my initial about my final was trying to let Internet energy initial is what 0 final or what might do well every my rocket launcher I'm goin was speed really so my final has won half what they got a much better with your energy for rosier 1 is rare think your potential and was raining initial I know it's Friday it is make my day why have you don't get delayed until you answer this question Final excellent potential engine gravity and shop let's take age equal 0 where we start 0 thank you final so the only other little trick in the prior month you gotta make yourself a triangle 30 degree 0 . 0 5 meters so equals 0 . 0 5 times sign of 30 Write to the joint up the ramp that enabled I put that altogether I'm one-half squared equals my 1 have And this word plus an injury each so I need V and I can find jutting because Equals And quantity squared plus 2 G H Over X where so that's what I need I make my lovely Kinematics triangle which you all remembered Go back and review kinematics not 1 have been Ottey 1 have square and I go 100 meters And I do this at an angle of 30 degrees I look at it as artist here a hint that he needed nomadic because it does have an initial and final has restored and has where we land you might try to use energy here the problem is I like going straight up air words all 1 direction Remember jet margins the parabola were going along a curve we have both a X and Y directions you have to worry about these kind separately and The rally There were a few ways Do yes Other than using your today Maddox knowing the time of flight and working from there but the big hit the kinematics not meant the would force auditors gravity point and I like it this change of 30 works well for me because of 1 one-half GTE squared off over a hundred meters so that a give me a time of 3 . 4 seconds It I wonder at the time lots elicited the velocity but 100 divided by coastline of 30 times tying his velocity speed of 34 meters per 2nd which I plugged in here and I get my of 9 . 2 times in the 4th New ends So that the calculation right there The calculation is not actually that Bonn Well longer than just a simple energy problem right of I told you I build a rocket launcher that has a lot of speed of 60 meters per prosaic at what they might 0 today before you are lazy because we still have 3 minutes ago it feels like had any questions raised through groveler plus what we do next week will be the key to look not read out a darn I did to problems were used almost every concept except friction From the course and just 2 problems in 15 minutes you're exam will be 2 hours of up to problems like this and it will have roughly short answer problems so this is what you want a program for the next 3 weeks to wait time a week and I do have others hours as our ways and role and not the
Magnetisches Dipolmoment
Satz <Drucktechnik>
Plattform <Kraftfahrzeugbau>
Elektronisches Bauelement
Angeregtes Atom
Rotierender Radiotransient
Gelenk <Technik>
Masse <Physik>
Basis <Elektrotechnik>
Anzeige <Technik>
Intelligenter Zähler
Singularität <Meteorologie>
Platzierung <Mikroelektronik>
Innere Reibung
Haspel <Textiltechnik>
Initiator <Steuerungstechnik>
Negativ <Photographie>
Homogene Turbulenz
Magnetische Resonanz
SOHO <Satellit>
Satz <Drucktechnik>
Klassische Elektronentheorie
Direkte Messung
Avro Arrow
Koma <Astronomie>
Front <Meteorologie>
Proof <Graphische Technik>
Scheinbare Helligkeit
Masse <Physik>


Formale Metadaten

Titel Basic Physics Lecture 22
Teil 22
Anzahl der Teile 26
Autor Dennin, Michael
Lizenz CC-Namensnennung - Weitergabe unter gleichen Bedingungen 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen und nicht-kommerziellen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen und das Werk bzw. diesen Inhalt auch in veränderter Form nur unter den Bedingungen dieser Lizenz weitergeben.
DOI 10.5446/12933
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2013
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Physik

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