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9/9 lecture on moving variables

Added Sep 09, 2020 •

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YouTube video take a look at rearranging a fairly common as kinetic formula and physics formulas one relates the average velocity to displacement when do you normally see this formula his average velocity is the displacement divided by the change in time now what we're going to do here is we arranged it for the Yelp in this class in Winter senior typically in our class in The Fosters I've learned we don't put it in a V4 average what we do is we would draw a bar over the top or just leave it as plain fee that is represented as an average maybe they make you cannot listen to his speech I think this is the Canadian version just by the way they say something so instead of saying displacement divided time are changing display the drive I change of time if they displacement divided by time now we haven't even discussed with this place and is yet so really just a distance that's right now and then speed so let's continue to see just how we rearrange is this detour to placement and they also were guilty and so let's start with his size formula here now if I want to rearrange or Soul or isolate for the adult then I want to get rid of this. on the bottom right now the deal he is divided into the Delta p and so the opposite of / Delta he would be there multiply both sides by don't remember there's an equal sign to keep it equal you have new equal things need we're going to multiply this side by Delta G we have to multiply The Other Side by Delta team and the reason for doing that is so that these Delta keys will divide out on the right side lane to me why the Delta team or cancel when you multiply a number is equal to 10 C multiplication is the opposite of Friday so when you would love to fly a number by the by the bowriders delta-t over gel fatiga cancelled out because that is equal to 1 simple as that and if we multiply anything by one of the change it is Delta G going to be changed if we multiply it by delta-t over delta-t which people to want no and that is the same thought process for setting up conversion X things that are equal to one where the top and bottom of a fraction are the same so that's why I was considered an adult the isolated so delta-v is a change in time x the average velocity now it just got here is something else he will commonly not seeing this class or in any physics class and text me use for a Time sign text becomes a variable in physics pretty soon when you get to the higher-level stuffy measuring things in three dimensions directions to mention your y Dimension and Josie Dimension so when we get that what's the measurements will be at that's our mission along the X Direction so that's why we don't use the time sign we would just write these next to each other so you're seeing something typically don't do in this class is it convention it's Norm rewrite this then as Delta Because of You song Or Nah lyrics on the left is the change in time x the average velocity and then the beginning of it you see things right here old school band what it means to be to use that back in the day in sign nobody in this class it means therefore I just means they're born so this means if Delta t x equals Delta D therefore we can say we can rearrange this and say don't the D first equals a v e x why would we do it this way because now we can equal sign right next to this values that we've already identified and step one you don't see that here cuz we're just rearranging and then we can come up with an answer people find volume of we no equal sign answer with appropriate units is a very efficient way to communicate with each other and physics so that everybody knows everybody's to it and that's how we're going to do in this class so let's see how he first if you want to convey normally the average lost keys were the first actually I could but a little bit longer I wouldn't start with this verse I start with this and the reason I would start with a because if I'm found guilty then all I have to do to get to help tailbone because the average loss is X right now is to the average of this release the opposite of divide and multiply the area plastic so the multiply Malia Ridgmar Movie to divide up the average velocity and the leaves divided so Delta 88 is the displacement divided by the average velocity or again they're putting the therefore now we can ride delta-t with Delta G over B just drop off the Deltas and we think he could be over fee and then we put an equal sign when do you put in what is Rd what is RB to put an equal sign I want to hear your answer with the appropriate units information down here than the useful for you so let's start out with just something very basically building off prior knowledge what is a variable a variable is a symbol used to represent a quantity that can change common variables in math PacSun you seen those one are you going to see a lot more in this class and I'll just Bland Datsun y very specific thing what are some of the common variables or call that you're going to see in the beginning of this class so the beginning of this class is the common one team for time is it lowercase or uppercase it's lowercase to uppercase t. That's a repeatable amount of time that's why you're in third. Right now it's a repeatable time. So capital T is for something else right now it's a very simplified kind of beginning of physics way to to represent his later on you'll get more specific with things and just using them Landy we use a lowercase b for speed for the speed is related to Velocity and it's lowercase because uppercase is Bali we can't use the Big D that's already used for something else and sign and then acceleration again it's a lowercase a not uppercase and that's YouTube so the lowercase a acceleration is in the beginning of this course but they might not appear to be very simple it might not just be me you might have little letters below your main leg what's this song what's a prefix that means below and below the writing you might see something claiming that you have there are more than one measurement of the same kind I like it we have two different speeds be measured we might have to use subscripts in stitches English between them and then to realize where we put that in an equation like for the speed if we have a beginning speed in an ending speed while we would just quit being V we put VI and VII the app is a real common one in this car the initial MD final initial meeting at the beginning final meeting at the end so when a car speeds up sometimes we don't have that beginning and ending but we have two different things like the mass of the earth and the mass of the moon when we're trying to find the force between the Earth and the moon the title forces that exist we would either use 1 and 2 or 1/8 Abby I really like these ones into M1 and M2 math 1 in Mass to you could say mass and mass be use a little A and A B down there that be okay too but when I start using letters down here they tend to look like these here so I can you use them for initial and final that's common but when I have two different things for masses I almost always use one and two now as opposed to a subscript we could also have numbers or letters that are above this typically it's numbers if we have a number that's above is normal we would call that famous super duper being a prefix that means above or Beyond what does a superscript on a variable mean what does that mean in a math class is superscript like a number on a top of a variable yeah, right so we know it's like squared or to the 3rd power SunPower a superscript means a mathematical exponent like when squaring a number like radial displacement how far is the measurement of distance to hear it says you go from where I radius begins on one circular object to where the radius begins on another circular object in other words if we want the radial displacement from the Earth to the Moon we went to measure from the store disappear the surface of the Moon we want the radio this place and where do radius is begin in the center of a circular object right radial displacement from the Earth to the Moon how it goes you're in the center of the moon in the year since it came up right now I wanted to introduce to you what that was but it's just a special special term for a real spell distance measurement for radio replacement I take my okay now what would a variable equation look like some of the common ones you see in this class look like this the top one being a very common one known is Newton's second law it relates acceleration force and Mass now the second equation a lot of you right now probably all of you are seeing a equals . - V over t yeah that might be what I'm seeing too but that's not what my brain is saying my brain is not saying a equals B at my Zio 40 years will my brain is saying it's taking this foreign language and it's putting it into English translating what does a stand for acceleration so acceleration is something divided by time do you remember what that is in this class Powerball what rate so acceleration is the rate at which velocity or speed this equation if I move the key to the other side how can i x i d f minus what does a force use for a Time causes a mass to change its speed that makes sense if you put a force on an object or a timing light changing speed like and push something it's game I change the method that object that has an application fee equation they really are descriptions of an of an observation and then we put it into a bathroom so as you start to look at equations a little differently than just a equals b f - p i / T this is known as the definition of acceleration acceleration is the rate at which velocity changes so we've got to look at things a little differently in this class will be moved from one side to another to the opposite side play Asian I've always remembered opposite side opposite map move something to the opposite side just do the opposite Matt that it's doing on that side so something's being multiplied on one side if you want to write down the other side to write it as multiply that one side body moving to the other side what's the opposite of what I move the a to the other side are you buying because it's being multiplied go on that first equation there Dubai to bring the a to the opposite side in the first equation above what would I do bring the r-squared in the opposite side of this equation 18 / are square so I would * x squared to the office in the last equation above the sometimes sometimes we have some ice cream let's start doing so the second equation that's the definition of acceleration acceleration is the rate at which how did that equation do you rearrange to find the S so let's equation 10 kg equal VF - VI / T acceleration is the rate at which teaching so what would be one you think would be one of the first things we can do to get BF all alone x x and we multiply this side by T we have to do equal things equal sides so we have to multiply this side by T Y does t / T cancel cuz it's equal to 1 - VII wood add bi but I've got a new equal things equal sides I got to add me either this side also - me I must be I canceled so now I just got BF and I know what is equal to a Time Steve Twitter Stephanie just went through first we move the key to the other side to the opposite side but doing the opposite math so since the original equation was a equals b f - V why Oliver he we bring the key to the office Inside by doing the opposite math since it's on that side dividing it's going to be multiplied on the other side then we bring the vi to The Other Side by doing the office in meth since subtract and then we usually write the equation starting with the thing that we have now solved it for what did we solve this one for does it say the people usually want that coming first so really the most common form of this you're going to see is BF bi + 80 Dia Eagles bi now we can say 18 * a + bi most assembled API + 80 because it rolls off the tongue easier than the other one that one is too hard we had multiply something in divide something receive the ad we are the X and then add something let's do another one let's do the second equation aren't you the Third how can the third equation from before do you rearrange to find VIA that equation was half equals m v f - VI all over tee if I want to get VF alone what's the first thing I can do to move videos. What do you think yep bruising I would do it be multiplying both sides by team 6 / t on this side profile on the TV move over to this side I do the opposite math to move into the opposite side first moved to the office this is super powerful equation physics right here now this is called the impulse momentum theorem it tells us that a horse used for a Time causes of Mass to change it to me that's something we observe we observe when a force is used for a time on a massive object object with mass that object changes its speed and here it is written in physic he's no it's not Chinese know it's not Japanese no it's not Korean is it's not about it's busy Keys it's a foreign language if you know how to read this you'll start to do better now if you just see that has variables in an equation that's a good start but when you start to see a Ford used for the map to change its speed you're thinking physics you're thinking what's happening what is this describing so next month can we move next we're trying to get the BF alone BM to the other side and we divide it connect movie and to the opposite side by dividing it over there so it's no longer here multiplying by the Via quantity call me on your cell phone on the last thing is the vi find a CI to the other side we so the last thing would be moving that VI to The Other Side by adding it and we get plus VI now the common way to write this CVS in Crosby I bust a steel rim VF Eagles VI WhatsApp tiagra one more and then I'm going to set you loose to rearrange all the equations we use this year how can the last equation from before that this one 5 equals big DM 1 m 2 / r squared we have subscript and superscript how can I be rearranged to find M1 first thing I would do is bring r squared to The Other Side by multiplying the yard Square was divided on this side x bring it over here now I'm getting rid of the Big G since it's multiplying what's the opposite of bring it over by dividing up the Jeep so you get past x r squared / Big G what's left over here how do I bring the M2 to the other side occupy you don't jump the track if you're not added they're being multiplied together to bring onto to the other side I divided wait a minute find me the / Big G goodnight have done Big G and M2 at the same time yeah you're going to go buy them both you can bring them both at the same time because they're going to both be on the bottom at the same time so now 5 / M2 to get rid of the right side on to the left and now I'm going to rewrite it in the standard with the Standard whey is writing what we solve for first and this case we saw rim because now we can equal sign next to this plug in our values and makes a very effective communication method in physics is that everybody doing things their own way and everybody making up rules in English that are their own rules. The Godfather same rules if you want to communicate effectively it's the same thing here so now you're going to get some practice the there will be a couple of things that will be added in the practice that we didn't talk about like what happens if I wanted to solve this instead of solving it for let's go back up here what if I wanted to solve this for our Square for our what would I do with the app play to the other side and then how would I get rid of the square root so that's not we didn't discuss taking a square root to get rid of a square you will be having to do some of that needing to do some of that with your homework rearrangement for cement second semester equation to see how you get it to go up in either Corner the classroom is that where she are you at the rest of the period to work on that I'll put up some of the answers if we go

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9/9 lecture on moving variables

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