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Metric system: units of weight


Video transcript

let's think about the units typically used in the metric system to measure and objects to measure an object's weight and I'm putting the weight in quotation marks right over here because the units I'm going to talk about are actually if we wanted to be technical their units of mass and as we'll see later on in our scientific in our in our scientific careers that weight and mass are not the same thing they are related mass you could view is how much stuff there is what's the how much substance does an object have how hard is it to change the the velocity of an object while weight is what's the force that gravity is pulling down on that object now in everyday life on if we're just on the same planet or the same part of the planet if something has more mass it's going to have more weight and it's something has more weight it's going to have more mass and that's why in everyday language these words are often interchange later on we'll see that these mean different things for the sake of this video because we're really just getting ourselves warmed up with some of these units I will use these interchangeably I'll use them in kind of the everyday language sense not in the technical physics sense of the word so in the metric system when people talk about measuring relatively light things they will often use the gram and to get a sense of things that weigh a gram one example is a paperclip your average sized paperclip would weigh about a gram a stick of chewing-gum not even the whole pack of chewing gum just a stick of chewing gum would weigh would weigh about would weigh about a gram a dollar bill would weigh about would weigh about a gram so this really isn't this really isn't a lot of weight now if you wanted to measure things more on I would say a human scale you could then increase by a factor of thousand and go to the kilogram kilogram and as the unit implies as the prefix implies I should say kilo a thousand this means 1,000 grams and if you want to think about how much that represents well many people will measure their weight in terms of kilograms so I for example weigh weigh about about 70 70 kilograms and I'm five nine and I'm about average average build and I weigh about 70 kilograms if you want to imagine what a kilogram is like imagine taking a liter of fluid so if you are a liter of water so if you took a liter of water so and a liter you can imagine as a ten centimeter deep cube ten centimeters wide and ten centimeters high if you fill this up with water the weight of that thing is going to be one kilogram and things I know you're not used to walking around with with with one liter cubes of water another way of thinking about it if you go to the supermarket and you were to buy a two liter of soda you were to buy a two liter of soda and sometimes you can buy two liters of other things as well water or whatever if you buy a two liter two liter of soda is going to weigh is going away well actually two liters of water in particular is going to weigh soda has other things in it so you can't you can't be as precise with the weight but two liters of sort of water I should say are going away are going away exactly two kilograms if we don't want to run it we're just taught talking about the water itself we're not talking about the container but if you want to get a rough sense for how much weight that is that's going to be two kilograms so if you're measuring you know human scale size things a reasonable size quantities of fluid objects around this scale kilogram makes a lot more sense if you measure these very light things you're talking about you're talking about a gram if you want to get really precise so this might be more in things if you're doing you know a drug dosage and you will need to be very very very precise then you will sometimes see people go to the milligram the milligram but you could imagine a milligram is one thousandth one thousandth of a gram and so one thousandth the weight of a dollar bill or one thousand the weight of a paperclip this is very very very very small so this usually doesn't come into play in our in our everyday in our everyday life