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Basic Physics Lecture 11

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Let's go right to the example we're going get Within the last last right now words is very bravely goin over the concept of Newton's 3 laws and we ended with
1 version of the 2nd lot that s Forces are interactions cause accelerations and the magnitude of acceleration It is proportional to the max and a standard situation you might have is where you know something about the acceleration and you're curious what force generated the motion it is as simple as most basic of new insect our problems because to answer at all you have to do is fine A and solve for F net April's MA So It's training straightforward but his and remind you and this is where we started 1st I did build put our ideas together
So in this problem you're given that you push about 2 meters That I think it because velocity but it started at rest Are Any goes velocity of 1 . 5 meters per 2nd so it starts here with equal 0 At moves to meters and when I get there and has The equal 1 . 5 meters per 2nd now how are we gonna fight and we We are told its constant acceleration Sigh we find a in this situation quickly do that a piece of paper faces a can of problems to take you last Then a minute And you should be . your wanted to remember 0 . a good start at 0 . 5 6 meters per 2nd where anyone tell me how they got it But a joke There's a lot of times and good to remember the equation we don't use a lot now ever made the right positive doubt acts as positive and speeding up the acceleration as positive there in the same direction so we get a positive number here and so A my acceleration v . 0 there's just 1 . 5 meters per 2nd squared divided by 2 2 times 2 meters and that me . 5 6 meters per 2nd squared and I was told the book has a mass of 0 . 5 kilograms of net Forests is 0 . 5 kilograms plans by 0 . 5 6 meters per 2nd square which is 0 . 2 8 new and any questions on that while Indian another way you might have found acceleration that it was kind constant acceleration But some other ways we find acceleration Changeable acid emerging entirely We use time to do it OK we finally was being not plus AT is another way of writing change in velocity over change in time so Everything we did for the 1st 3 weeks will come back at our forests From problems met that's a set that what it tells us what happened notice the 2nd walk A Reeve right here had 2 features and it There we have focused on the about the total force And there actors so we worry about the total force that everything up And they're vectors so we have to add them as vectors which usually means Looking at the components now just do Confuse you you will occasionally be asked While word Makes our a share Begin Due to widen particular force and that is still given by after that force peoples and a court particular you have a If you have a bunch of forces acting on you and you're not interested in your actual acceleration use 1 now if only the 1 force was acting What is my acceleration I still use of them but Keep in mind when you talk about the acceleration of the object that That only means really total excel in your 1 actual acceleration which is your total you might have lots of forces acting on you to give you that will accelerate and that's the the trick and how do we find all different forces And the answer to that is the 3rd walk And the basic principle and most you got his right on the Lanquist quit is Any to objects that interact Produced a single force between them or a single interaction and that's what you wanted might as we move in a force Problems it to abject making a single force and the picture we constantly drop It is object Eddie object indeed They interact and that gives us a forest INA due that is equal in magnitude of forests on being dude egg and the only trick is there always at opposite directions of the 2 objects pulling on each other they together their personal each other they move apart and If you want to know what happens to be you have to ask whether all the things be interact with For everything is interacting with Because the 3rd lie you get 1 4 and then you had a 2nd line you add up all those forces You never use the word law the figure out how to groups known Robot was nothing about acceleration there is no acceleration mentioned anywhere here in the 3rd so you find yourself saying something like well do the 3rd off the forces are equal and opposite so they canceled the at 0 so the acceleration 0 what misstated adjustment I I used so far but to make an acceleration you cannot do that you absolutely never ever ever ever ever do that what you do is use of 3rd defined although Forces on an object and then from there the user set a lot for that object and you have to keep the 2 separate now as you might end up the course of a problem finding out all about an 8 so eager find out whether this there's so you can find that forces and be a man using the 2nd modifying the motion of Big so you you you might be multiple steps here but
This tonight For the 3rd lot idea Is always just Find all the forces on a beach So Any questions on that Yes Oak Request is the definition said that when I did it I mentor I forgot I knew it was a fine to be a kilogram times a meter Divided by 2nd square dances the definition Other questions Yes yes Apple's It was the major Yet 1 So a review would not abide forgot that the value linear 1 as the negative rather workers earn opposite directions but I really like to keep it said the Mac same the directive drops Instead a minus sign is fine for me conceptually that helps Keep Chris liquidity negative you Notowich direction APEC as positive Vermont A mail Were in news and demos today But well Morgan a looking for the next tour weeks or so Oregon and doing problems that use peoples and they now we did the 1st 3 weeks of problems involving a So A lot of the ones we do more connected back Probably the 1st 2 weeks of this two-step The problem through starting with forces defying ACD diplomatic remember doing kinematics defying a solidifying forces at will be the connection between the 2 problem now however there work whether some of the questions you wanna be looking for work That's how you're doing forces while 1 is the trivial ones where a rarity did as 1 you know away or you find that from gender Maddox or some other way and you're asked for the total force right that's just plug into an was and made what makes that 1 the hard maybe it is you might have an object moving somewhere a you know how long it took to go some distance and because it was being pulled employers and the gravity in all the stuff friction and You need to put all that together the fine day the total force a slightly more subtle 1 no way or you'll have to find it and you'll be asked For a missing force This type of problem is 1 where not interacting with multiple things you really wanna know what the force between 8 In another object Example might do to football players collided on a football field and Laforrest between them and you know the friction with the ground and what you wanna do you know the acceleration we wanna find that missing enforced by just 1 missing forests and I know the acceleration I will be using at people man Defying mechanism for so a bunch of forces summed up by the 1 will be missing I will know Eddie And I can't solve for so the variation on the 1st problem now ever this is our 1st down on a moment you might know way or find it city near NEOB asked if something breaks A fright Most objects right when subjected to enough Force should write but this is a paper Instead of accelerated broke I'd like to know when that happens and so hard as that happens that happens when you try to make an acceleration that has to do so again what you do is you plug in that was a you find out of course is required if the force required to make that acceleration is too big for the object trying to generated the object right at the other type of problem we would be doing is also be very common if you're building stuff Yeah I learned the other day 25 per cent of our bridges in California Are not considered state structurally Yet before stance of getting home safely shipped across a bridge The area was dinner very described it as does every time you go over bridge count and on the 4th 1 algebra and occasionally You end up knowing the net force are you found it from some reason And you're being cast defined the acceleration often enact Lou Reed has climbed so reticent Because of forces of constant you're actually wanting to know about the motion your nowhere land how far away how high it went with speed it was landing at what angle in it with But you're used kinematics the solves the problem but to do the kinematics unity day so it won't actually asked for an 8 or ask you for kinematics type question knowing you need a you can get from the forces employee and that was a mail Any questions and those things so that's what you wanna be looking for For the next few weeks yes there While using given the minimum force required break it So yeah that that will have to be 1 of the game that how you know you're in that problem it'll say something like A rope can only support a 100 new and Spider-Man 3 on the road there's breaker Not that like a classic eulogy the cars in Spider-Man swinging and the rope breaking they're the ones we may suffer at It is not the cat someone like this when you find and that the hold someone else And as a break for Chris It you know we don't like to put kids on swings I know my ever breaks land not such a big deal they bounce object so Renew our 1st questioned how started but I would come over here and explain it so what we have going on I have a large mass here
Amitabh Jewish drained And so hanging from the top strength
I want to be doing is using the bottom string to pull out of my Bahrain and call the strength and the question is I wanna pull it in such a way But the top wire breaks and not the bottom wire That's my goal so pulling added if I will eventually won the 2 wars over it
Right I want to make the top wider braided my choices are quickly write top slowly would break it The choices either it's always been a breaker never got a break and as a matter of how Asked by 12 Show That makes them I'm either Interpol real slowly Er manager quickly and well-equipped jerk break the top wire will slow pull break the top wire or Is a time not matter no matter which way I do it is the top a break Or the bottom line We are school a couple people refusing to answer enough so let me do this
I'm going to do
Make quick Emerging Before I show you the answer so this is pulling it really quick ready
So I pulled it really quickly and the top order that outbreak CERCLA quickly does not break the top right so the vote again We will limit 1 answer was slowly break the top wire or does the time not matter Interesting so it looks like what would like is how money with thought quickly have now decided time does not matter So everybody thought quickly when the salon In earlier lots Lord that time that matters that would be good if we lost all the way that thing we did was tied the knot matters Changes So let's do slowly
Maybe So that's out why rates 1st Yes but is not a dance and trust me it's not magic
So why does have And at head and the heart by the way you want talk about practical applications of physics Probably In the most dramatic application of my mind I knew it was Lauzon forces is almost everything in martial arts or karate is actually related and works because of new and secular law and 3rd Bob and what's happening here is is a standard A situation where rely lot At the ball in the center and all the interactions on it so badly that the bomber center and dry weather we will call a free body diagram I draw the interactions of 1 for me pulling down there was 1 for gravity and then there's the string attached to it That's pulling up tourists 3 interact that's 1 thing you gotta get used to that reasons as gravity there you'll learn to identify that we want identified pretty much anything tucked in an object interacts with it 2 strings were touching So at least those 2 interactions gravity because we're not putting space now I could write views as recipe for pole and subdued for gravity moderate U.S. view for up and I had these due to gather underscores of deeper down citing as simplify my picture ever down forests and force and so might show of force now let's say But to be positive So my total force As whatever the size of the minus the size of of the down And that a legal masked and acceleration not everything is moving into 1 direction here so I don't have to worry about the vectors anymore I called us all a wider action the label that The viable again My my weight class when I'm pulling away A rat cycle the gravity here miners gravity pulls what I'm pulling away It is able to South Putting those together let's look at the different things that can happen what is the definition of acceleration again End Change in velocity over 2 days test The job noted that I have a very short time which means I pull quickly then I have a large acceleration for a given change in velocity So did some change in the losses that I'm trying create a I triangular really quickly my acceleration is large and it is down so we're like that Putting these 2 things together right I take a large acceleration I put it in here that means vest gym They have Has Be much bigger then my force Up given that the strings were the same through a break with the same force which draining experiences the much bigger force in this case the bottoms of the suffering shrink the bottom positional awaits there It's still as so much better the weights and constant value the bottom string will break 1st if I do it quickly enough Now on the other side If I do it slowly then doubt that He is a big is small and now might Force if I take this equation is equal to whatever that acceleration plus whatever gravity years What I'm pulling And if this is pretty smart Now this starts manner and Might force is bigger than my pulling force But now which 1 breaks 1st which 1 of the bigger 4th copper-bottom thought so that breaks for 1st these kind of arguments Barbiturate and they will show up in the course About problem that you're doing to get numbers so you do want the pay attention for this kind of thing you'll see it Come up and you wanna watch for When we do problems for any questions on that If Now I wanna DOS fairly similar things with his book Oh yes yes All But Were not what Well At the Tuesday Process right what happens is and this is why it makes the argument a little tricky 8 I'm attempting to accelerate the ball with a large force and scatter the weird thing about physics so Europe your mostly right but the logic is theirs You 1st need that 1st step of trying to make an acceleration here To achieve that before pulling down has to be bigger than the force the top otherwise It want accelerate however as I'm trying to generate all that for the 1st half happens the string breaks and wanted break but the hanging there and string doesn't get any bigger forces that and stays the same A lot of the forces But not all of it because And it's not all translated because this is starting to accelerate this was an accelerated if I was like holding the ball with my hand to make sure it never accelerated their whether I pulled faster slobber bottom string would always break so that's kind of the subtle difference it's starting to translate the force but the bottom line is getting bigger faster than the top 1 and breaks 1st and then no more forces transmitted the the the kind think about it All of you but you could believe that if I had strings which I think I'm out of
Unfortunately is a leading before Of all we know I can do it fears of renewed strength I use I see the demo So it was a brand-new string on the top A string of 30 venues principle in your theory is true it's much weaker now Bible School in part still breaks like registering So it could still work so it really does work and it's really why an expert in karate can break bricks and break would it all to do even others the same and hitting the same logic is a forest between has
With the relative attempted acceleration the time involved the time contact A lot of the things like that so the question I have for you now
I'm a but and that is Runner at a mad if you believes that the visit was a tablecloth And the book is all the China on the table and magician and I had any skilled whatsoever So I will quickly out and none of the China falls over Is that exciting I will slowly And all the China falls over John Madden that right Where put that in post-production So What is that Talk of and next to to you see my argument for the breaking of the strength why when I pull slowly the book slide But when I pull quickly But paper comes out A
At that time She it's not a Just hot Society spots are why the quickly pulled paper comes out And the solid wallpaperer varying stays behind Less brought When I told last Yes less I believe that I figure is we got it was that everyone we really careful any heroes or what I was saying gotta wounded and set a lot in for box notice about the book Iowa 1 interaction that's what the paper for the China with the tablecloth now relearning kinematics that X a wider Rettinger independent some only word right now about interactions there is interaction with gravity will come back to that later next week I don't worry about that now Only worry about the book movies in the x direction so is asked those interactions of IN the paper company interactions do I have Bob be careful how they interact I have 3 what are they not ravages get direction it was not a trick question my hand but And the book you gotta remember the tables of the paper does interacted with Now what is his mean notice The interaction between the paper and the book is the exact same magnitude asylum force between the paper in the book That is the same as the book on the paper this Abbas 1st Judith friction which we will learn has a maximum value exceed some number so when dealt the CIA's smile and a is and is case of When I will call the attempt Is to read that actually Chen not our offer and that I did this solid red Because It is really very hard I think to think about right but what is going on in the paper's going to accelerate no matter what because I am calling on right so the paper Is stocked with these 3 interactions so it has ever called and then they'll be interaction with the book will be in the opposite direction interact With the cable being gobs of direction and the B sub and But I can make that is because I want Any aid that I while I can achieve that I have no doubt the friction and Polo harder than I would have there was no urgent but I can't do it for the but the only force that is of course on the book due to the paper The question is big enough to do the same acceleration barrels The paper can accelerate as fast as the than the book can be moving with the paper all haven't given velocity gets left behind the beer make the acceleration the the paper so that that that much bigger than the book You don't even notice the but accelerating before the papers and the force of the but is 0 rout And stop moving A friction that start The source moving carefully because it does at the table at bat As 1 of those conceptual types of thinking you're going to do when you face at peoples and they problems as think about And attempted acceleration and ask the question does it or does not occur and that's where these problems yet I think the most challenging as we go forward was a man whose and I used to think about that See if there's any what happened but that doesn't happen or not That's kind of a challenge So it I Kolekar question relate to that if there's any other questions on the block That is the engineer was slowly wet As the ultimate limit cars acceleration engine torque and power so He reminds us that exporting cars the engine torque is based on the force generate the toward engine rotates in rotational force look toward the engine power power is energy per unit time rebound done energy yet but powers how much energy you can generate a certain amount of time tire virtually the rout Water Bastard Then with gas At then with 0 regard actually most people the Pfurtscheller right and again This comes from thinking about the interaction I have a car the only The former is interacting with It is Brown right here is is only interaction every Houses inside the car and part of the car interacting with itself so the only thing that can generate a course that moves the forward Is the tire with the row joining a generator force that whose mean forward If the ground which on a about trying to decide I wasn't very careful Islip don't go forward because I get force on Zogby pushing on the ground the ground forces me when I put on the ground I move the ground courts because my personal around some around not to make a question that now we had the volunteers for demos
If they would please come down Our demo volunteers
Badly I say yes Eds That had you say If Floyd his lovely nature of friend has your quicker as 1 myself but a friend put your quicker for you just don't get messed up you take the rubber stand on that very safe device
With reels under that have right now just Can contribute stand this to thank for that yet See either 1 and that went for now that you guys hold this row Forget Excellent so the question we have the steadier posed for a moment
Set Now Morgan have the 1st in the single worst that
Person a I I wanted to make up a massive group here and a less massive group years so You're going up will you guys Just cannot hold Is he get offline for that day by day and offline him or both going to move that your voting So I remember you as it is balancing just hold the rope Europe the road and I'm really hoping the wheels work because of mail miserably of the whales don't work sir keep your fingers crossed their work too well somebody off all over but that's a separate issue 5 bar rig
And Your saw prediction is OK Eva Either he only his number Where were diverted to their is Dolly What the budget guide
All the Robertson weapons had made we Step off please go back I knew this would happen with the carpet the wheels generate a lot of effort a bucket too many people doubt that try again Oh you stand in the middle were islanders above in the floor there's a bump in the floor trust me that's a problem as try 1 more time The riddle see these were read Drive removed a mop up actually I know what really don't forget but your card Underwood let's get rid of all bumps in the cockpit Back now we got it up that guest and now Now they won't know what happened white I would I'm the 1 who move last So we're actually finding out about friction I'd I'd argue by workers was expected but were flying have average and that work well in drug demand with 1 more They will fully healed every few minutes when you guys go back and see how sell joint catcher's throw Your wanna throughout at eager to catch so why you go you go ahead and stand on these lovely cart on the down would record balance His Wagoner volunteer Baghdad is right Why is it that way before you go what is that have only can't block let's say ready drama Bob Again like a Barry will be right there that On the sorry that probable already Cagney was at work at my
I decided I got remember directive it was not his draw there was a problem it was my directions stock while we were looking at their it's very important to take home Following 2 messages from that we were focused on 2 Rev. things right
The interaction between the 2 people when they pulled on the road this is answer lot there is an equal and opposite force here and I actually do it this way as one-time what I focus on a single person I now have to ask about all possible interactions and I also have to ask about the Mac's because a attack earlier fact Of the Depends on the massive independent had all up to does when there was a lot of French in here when the 1 part was on the carpet that causes a lot of problems right to notice that there was a force pulling them forward as soon as we put them on the on the 1 hand and got rid of the friction force on this person was obvious what's amazing right and this is something we often forget about Is that person was pulling on the right and the 1st thing we saw a lot of Virgin was it was their part this way Right there was no obvious then they would throw the force this way We were having him pull that way As soon as he Writers Susan This person and pulled this way down the road there was an equal amount of force But due to the row And that is why they moved into you really have to be careful using new what if that set up these interactions between people and other big thing Saying they have with the ball right we threw the the ball there is now an interaction so there was of course backwards on the person that only really showed up when we got rid of friction or we may the 4th big enough food Now the final point of all this and visits with ropes Burgundy special for us here ever watch for that they're gonna be massless and they simply connect objects so the rope itself is like 2 obvious retired so these 2 Letcher sticking together will give you that Rio conceptual groundwork for all the details on the Internet
Schaft <Waffe>
Greiffinger
Außenbordeinsatz
Magnetisches Dipolmoment
Akustische Mikroskopie
Mechanikerin
Gürtelreifen
Störgröße
Satz <Drucktechnik>
Minute
Leistungssteuerung
Leitungstheorie
Computeranimation
MAC
Schlauchkupplung
Rotationszustand
DVD-Player
Prozessleittechnik
Biegen
Vorlesung/Konferenz
Knoten <Astronomie>
Abwrackwerft
Personenzuglokomotive
Eisendraht
Elektronisches Bauelement
Urkilogramm
Übungsmunition
Angeregtes Atom
Reaktionsprinzip
Eisendraht
Satzspiegel
Motor
Römischer Kalender
Jahr
Ringgeflecht
Frequenzumrichter
Rotierender Radiotransient
Drosselklappe
Gewicht
Fass
Ruderboot
Masse <Physik>
Stringtheorie
Wetter
Dienstag
Armbanduhr
Begrenzerschaltung
Feldeffekttransistor
Digitalschaltung
Zylinderblock
Kopfstütze
Elle <Maßeinheit>
Chandrasekhar-Grenze
Verpackung
Kombi
Satzspiegel
Beschleunigung
Tag
Rauschzahl
ERS
Druckkraft
Schiffsklassifikation
Gleichstrom
Innere Reibung
Ersatzteil
Steinmetz
Erder
Kugelblitz
Konfektionsgröße
Rutsche
Cocktailparty-Effekt
Kaliber <Walzwerk>
Lenkrad
Beschleunigung
Woche
Fahrgeschwindigkeit
Seil
Elektronenbeugung
Array
Cockpit
Kaltumformen
Sommerreifen
Feldstärke
Seil
Unwucht
Diesellokomotive Baureihe 219
Papierindustrie
Schaltelement
Kardieren
Säge
Handwagen
Direkte Messung
Anstellwinkel
Synthesizer
Direkte Messung
Teppichboden
Kraftfahrzeugexport
Bergmann
Besprechung/Interview
Erdefunkstelle
Nanometerbereich
Bombenflugzeug
Wickeln
Spiegelobjektiv
Spiel <Technik>
Urkilogramm
Motor
Kommandobrücke
Radiergummi
Steckverbinder
Innere Reibung
Kraft-Wärme-Kopplung
Waffentechnik
Windrose
Nichtlineare Raman-Spektroskopie
Elektronen-Energieverlustspektroskopie
Gruppenlaufzeit
Nahfeldkommunikation
Takelage
Blechdose
Niederspannungskabel
Gas
Flüssigkeit
Nassdampfturbine
Scheinbare Helligkeit
Zylinderkopf
Source <Elektronik>
Masse <Physik>
April
Papier
Dipol <Nachrichtentechnik>
Generator
Schraubendreher

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Titel Basic Physics Lecture 11
Teil 11
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 10.5446/12922
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2013
Sprache Englisch

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Fachgebiet Physik

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