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英制與公制單位 (英) : 英制與公制單位
- We're asked to sort the following units of measurement
- into two categories: U.S. customary units and metric units.
- So these are just two different systems. You'll get more and more familiar with them.
- Then indicate whether each unit measures length, weight, mass, or volume.
- Let's do the first. Let's see which of these are U.S. customary unit versus metric units.
- So the liter is a metric unit.
- You would use it in the metric system.
- A gallon is a U.S. customary unit.
- We've been dealing with that.
- If you fill your gasoline in Europe, you're going to be
- filling it in terms of liters.
- In the U.S., you're going to be filling
- it in terms of gallons.
- And we're going to talk about whether they're units of
- volume and whatnot in a little bit.
- Decigram, that is metric system.
- In general, whenever you see these prefixes, deci, centi,
- kilo, you're dealing with the metric system.
- No one ever talks about a kilopound.
- I guess you could, but no one really talks about it.
- Same thing, millimeter.
- This is metric system.
- A gram is metric system.
- Meter is metric system.
- The foot is a U.S. customary unit.
- We'll talk about whether it's distance or any of that in a little bit.
- Kilogram, once again, it is metric units.
- In case you haven't gotten what I'm doing here, blue for
- metric, red for U.S. customary units, or I guess magenta.
- Centiliter, that is metric.
- Centimeter, meters are metric.
- And notice we have the prefix in both cases.
- Centi means 1/100.
- Cup, that is U.S. customary units.
- I have to do that in the magenta.
- Cup, U.S. customary units.
- Meter, that is the metric system.
- Pound, U.S. customary units.
- It's getting a little tedious.
- Inch, same thing, that's what we use in the U.S. Ounce, we
- use that in the U.S. And then the yard, we also use that in the U.S.
- Now we've divided them up.
- All the magenta ones are used in the U.S. All of the blue
- ones are used really in the rest of the world, and
- actually some places in the U.S. as well.
- I think a lot of the world is frustrated that the U.S., that
- we're not all converted to this because the metric system
- is actually a little bit more logical.
- It's easy to just figure out what it's saying, and we'll
- deal with that in more detail in the future.
- Now the next thing we to figure out is whether
- something is a measure of length, weight/mass-- and
- they're not exactly the same thing.
- Mass is how much of a substance you have.
- Weight is how much force with which gravity is pulling on that mass.
- And it would change depending on what planet you're on.
- But on Earth, they tend to be used interchangeably, so we'll
- use it roughly interchangeably here.
- And then you have volume, or how much space something takes up.
- So this is distance.
- This is moving in one dimension.
- Mass is how much stuff there is.
- Weight is how much the force that stuff is pulled on, on a
- planet, by gravity, or I guess a star anywhere.
- And volume is how much space does that stuff take up.
- Now let's think about it.
- Liter is volume.
- This right here is volume.
- How much space do you take up.
- Gallon is also volume.
- That's in the U.S. and in Europe, or in the metric
- system, it would be a liter.
- That's a gram.
- Gram is a unit of mass.
- So decigram just means 1/10 of a gram.
- Meter is a unit.
- Meter right here, that is the unit of distance or of length.
- Millimeter, milli means 1/1,000 of a meter.
- Foot, that is also a unit of length.
- Kilogram, that just means 1,000 grams.
- Kilo means a thousand.
- Gram, we already said, is a unit of mass.
- Centiliter, that means 1/100 of a liter.
- Liter, we already figured out, is a unit of volume.
- Centimeter, we already figured out.
- Meter is a unit of length.
- Centimeter means 1/100 of a meter.
- So this is a unit of length.
- Cup, we've seen multiple times already.
- It is a unit of volume, how much space does something take up.
- Meter, that is length.
- We've seen it multiple times already.
- Pound, that is actually a unit of weight.
- An inch is a unit of length.
- We're all familiar with it.
- An ounce-- you have to be careful here-- if someone just
- has an ounce, that is 1/16 of a pound.
- It as a unit of weight.
- If it was written fluid ounce, then we'd be talking about
- 1/16 of a pint, and then it would be a unit of volume.
- But since it's just ounce, it's a unit of
- weight, 1/16 of a pound.
- And then finally, a yard is a unit of length.
- And we are done.