raise the roof on this party 494 Ines is how many kilometers Dr Kelly you didn't tell us we were going to have to do anything with the imperial system I mean after all isn't the imperial system only Superior for baking everybody write down Beast Boy well I will give you a pathway between metric or between the SI system and the imperial system on exams it'll be given to you in the problem on the homework they'll have a little table for you um if that fails you can always ask Siri right what I have told you here is I've told you that 2.54 cm is equivalent to one inch so I've given you a pathway well in chemistry whenever you're confused and you don't know what to do the best thing to do is to start working and you're usually going to start that process with the number you've been given so you're told that you have 494 in you don't want unit of units of inches so the very first thing you're going to do is you're going to get rid of those inches so we're going to place inches down here where they cancel out all right what do I know about inches well I know 12 inches are in a foot but I don't see any feet up there and I'm not sure where I'd go next oh wait they told told me that 1 inch is 2.54 CM so I can go from inches to CM keep the numbers with the units they have in the relationship the relationship you were given tells you you have one inch for 2.54 CM so I've gone from inches to centimeters here right well I don't want centimeters so guess what the slash pattern continues I have centimeters here I don't want them so I'm going to place them down there well what do I know about centimeters well by definition I know that a centimeter is 10 the2 meters so I know the relationship between centimeters and meters so now I've gotten rid of centimeters and I've gone to meters but hey meters isn't the unit I'm looking for so I'm going to have to get rid of those meters those meters aren't doing me any good what do I know about meters that might me do me some good well hey I'm wanting to go to kilometers and I know the relationship between kilometers and meters I know that a kilometer is 10 the3 meters keep the numbers where they are defined by your relationship that prefix and that power of 10 can't be on the same side side since meters are on the bottom that power of 10 has to go next to it so now I've canceled out my meters and I have kilometers so now I'm going to multiply everything on top divide through by everything on the bottom so 494 times 2.54 times 10 to the -2nd divided by 10 to the 3 power and that gives us a calculator lie it gives us 1. 25476 * 102nd although you're calculator may just be reading 0.125 476 right gives you one of those two things there for the first time doing the unit conversion we're confronted with a significant figure issue so let's take a look at our significant figure issues we have three significant figures here and most of the time you go from English standard to metric it would be measured however they've begun defining a lot of those relationships now one inch is now exactly 2.54 CM that is the new definition of an inch the Imperial system's actually gone back and redefined a lot of its units based on the metric system um excuse me based on the SI system so that's exact well that's exact and that relationships exact so our only measured quantity right there is three significant figures so our answer can only have three significant figures one two three round on the basis of that four so we wind up with a final answer oh and I almost forgot my units which was the point of the whole exercise there all right let's do another one pause me and take a stab at this yourself okay you know the funny thing is I tell you to pause and I actually get quiet a little and and stop talking um like I'm in class because that's just what I'm used to doing so I've actually been sitting here for a couple seconds quiet staring at the Ste at the problem which is why this video had the awkward pause in it but now I'm just creating a even more awkward situation I'm not a great social skills person and anyway we're going to start our line with what we've been given so I'm going to start my line with 3594 time 10 7 leaders I have no idea how I'm going to solve this problem but I know that if I start with picol leaders then I need to get rid of them so I'm going to place picol leaders where they cancel out well let's see what do I know about Pico leaders the only thing I know about Pico leaders is that a pic leader is 10 -12 lers so I've gotten rid of my Pico leaders and I've gone to leaders now I don't want leaders so once again whatever I have here goes down there so I'm going to place my leaders down there where they will cancel out what do I know about leaders I know lots about leaders but eventually I'm needing to get to gallons what pathway did they give me to get there I don't see leaders in that pathway but I do see a relationship between quarts and milliliters well I know a relationship between milliliters and liters I know a milliliter is 10 the3rd liters so I can go to milliliters so now I've crossed out liters and I've gone to milliliters I don't want milliliters so once again I'm going to place them where they cancel out Wella that was not a good color choice place my milliliters on the bottom so they cancel out and now I can jump to the imperial system and I can go to quarts I know that one quart according to that is 9463 53 milliliters there's a classic example of a situation where our English tetric is a measured quantity by the way so now I've gone from milliliters to quartz now I just need to go from quartz to gallons well I don't see a relationship there that's been given to me but I do see that A quart is equivalent to two pints so I know I can get to pints I don't want pints though so I'm going to place pints down here where they cancel out oh I see a relationship between pites and gallons finally so I place gallons up here where I want them and I know that eight pints are in one gallon so I'm going to and gallons are the unit I'm looking for so must be done so I'm going to multiply everything on top divide through by everything on the bottom that's going to be a rather substantial problem here 3594 whoops four and that gives me an answer of 9.4 943 4302 * 10 the 6 well now we have to do our significant figures our initial measurement here had four significant figures that's an exact relationship that's an exact relationship and here it's actually a measured one and you can tell just from the number of digits they gave me down here but they gave me six this is exact this is exact so we have six and four measured numbers four is the least so one 2 3 4 so our answer is going to wind up being 9.4 94 * 10 to the6 yeah gallons one thing that I often find is people will sometimes have a lot of trouble actually getting these into their calculator here let me go through real quickly how to put these in your calculator and to do that I'm going to clean things up just a little a little bit here that I have some room to write so that it's not terribly messy for you I'll create a video on putting these numbers into our calculator calculators for you as well but right now we have if you're using the class approved calculator you're on three 3594 you're going to use that e button that you get to by hitting the second key and then the X to the neg1 key right it's the shift function over x to the neg1 so 5 3.59 4 e 7 then you're going to hit times 1 e e -12 remember that e key puts in 10 to the karat for you so if you put that e key puts in times 10 to the karat for you so if you put 10 e then you're multiplying 10 by whatever value you put in there so if you use 10 instead of one you have an extra value of 10 so don't push 10 e push one e to get that number in right there then divide by one e e has to be one not 10 e e -3 divide by 9.4 6353 times to divide by 8 remember your calculator doesn't know what's on the bottom and what's on the top so you have to tell it that it's dividing by each one of those bottom numbers you can't just multiply everything on top hit the division symbol and then punch in all the numbers on the bottom multiplying by them all doesn't work like that your calculator doesn't understand or know what you're doing all right so that's it for that example let's take a look at Stormtroopers write down Storm Troopers once you've written down Storm Troopers pause me and take a quick stab at this all right I was about ready to do it again where I get all quiet while you actually pause me but so I keep forgetting that you can actually hit a pause button on YouTube if the moon is approximately 239,000 miles away from the earth how many millimeters is it from the earth so we're going to say 239 th000 miles whatever unit I start with I want to get rid of so I'm starting with miles so I'm going to place miles down here where they cancel out what do I know about miles well hey I know a relationship between miles and kilometers so right away I can get out of that imperial system and into the metric system system for the system day international which ironically was carried throughout Europe by an emperor um Napoleon forced it upon all the countries he conquered which is why all of Europe uses the SII system but in fact make you cool at parties we've got kilometers here we don't want kilometers we're being asked about millimeters so we'll place kilom down here where they cancel out what do I know about kilometers I know their relationship to meters I know that a kilometer is 10 the3 meters I don't want meters so I'll place them where they cancel out I want millimeters and I know the relationship between millimeters and meters so now I have millimeters so now it's a matter of multiplying everything on top dividing through by everything on the bottom so 23900 0 and that gives us 38 4 6 7 7 time 10 to the 11th technology is great till it's nine to the 11th again sigfigs we have three sigfigs there this is measured we have four sigfigs there the rest of our relationships are exact so our least number of sigfigs is three 1 2 3 so 3.85 * 10 the 11th millimeters is the distance from Earth to the Moon chemistry is easy life is hard