The **International System of Units (SI)** is related to the metric system and is based on seven base units.

SI Base Units

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## SI Units Concept 1

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When it comes to many of the calculations you're going to see in chemistry science related courses and math courses. You're going to see that the metric system is oftentimes used now the international system of units as I is related to the metric system and is based on seven base units. So here we have our seven images connected to them. Are there physical quantities? Names and symbols for the first one we have an anvil and its physical quantity is discussing mass for mass. The name of R. S. I. Unit is kilograms. And the symbol for kilograms is K. G. Next we have our ruling which represents length. The S. I. Unit for link is meters which is represented by M. For time. The name would be seconds. Seconds is illustrated by S. We have our thermometer which deals with temperature. We know that there are three units for temperature, kelvin, Celsius and Fahrenheit but it's Calvin. That represents R. S. I. Unit and its capital K. And then for remaining three we have the amount of a substance which is, the mole will go into great greater detail about the mole. Later on, its symbol is just M. O. L. Now you're gonna see sometimes when we're doing chemistry calculations we might write out the entire word mole or you might just use the symbol M. O. L. They can be interchanged with one another. Now next we have electrical current which is amperes and that's just capital A. And then luminous intensity, the brightness of a light source that's done by Candela, which is C. D. So these represent our seven S. I. Units that you should commit to memory. And as we do different types of calculations. Oftentimes we'll have to incorporate them within our calculations. Now that we've seen these examples, let's move on to our questions. We're gonna investigate more about the S. I. Units.

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## SI Units Concept 2

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now that we've talked about S. I. Units, we can apply them to other areas for a classroom. For instance, we're gonna say here that we can take the S. I. Units from up above and relate them to perimeter area and volume first, let's take a look at perimeter, perimeter can be thought of as this distance around an object when it comes to a classroom lecture hall, all we have to do is add up all the sides of the object or figure or in this case the room to determine its perimeter. So if we take a look here are typical classroom is 15 m by 10 m to find the perimeter. We just add up all the sides so that be 15 m plus 10 m plus 15 m Plus 10 m. When we add them all up together, the perimeter of the classroom is 50 m. Next we can look at the area of the classroom area, can be thought of as measured surface of an object as length squared. Now it's not actually just length squared. The formal formula for area is area equals length times with so that same classroom. Now, if we look at it in terms of feet, We could say here, let's say that we re examine it in terms of feet. And we found these new measurements and let's say that the lengths were 48 ft And the wits were 32 ft. So we would take 48 ft Times The 32 ft. And that will give us our area when we multiply those two together that give me 15,. And we're gonna say here that if we're multiplying feet times feet that would come out to be feet squared. Here. We're not worrying too much about any greater detail. Our area here for the classroom would be 1536 ft. Finally we can talk about the volume of an object if we're looking at volume, volume can be thought of as the space occupied by a 3D object as length cued. Now in actuality, the real formula is volume, which is V equals length times width times the height of the object. So here we have an example of a cube we say here that its length is these 15 m. It's with is 10 m and its height is also 10 m. So multiplying these together 15 m times 10 m times another 10 m. So we multiply that all together, that's gonna give me 1500 and since it's meters times meters times meters that becomes meters cued. Now notice for our area and our volume. We talked about length squared and here we have feet squared and here we talked about link cubed and here we got meters cubed, taking the S. I. Units that we examined up above. Again can be used in a lot of different ways here we're using it to determine the perimeter area and volume of different objects. Now that we've looked at this example. Move on to the practice question on the bottom of the page

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Problem

Based on your knowledge of the SI base units, determine the units for the area of a typical chemistry laboratory.

A

m

^{2}B

ft

^{2}C

km

^{3}D

in

^{3}Additional resources for SI Units

PRACTICE PROBLEMS AND ACTIVITIES (15)

- Identify each of the following as measurements of length, area, volume, mass, density, time, or temperature: ...
- What SI units are used for measuring the following quanti-ties? For derived units, express your answers in ter...
- What SI units are used for measuring the following quanti-ties? For derived units, express your answers in ter...
- What SI units are used for measuring the following quanti-ties? For derived units, express your answers in ter...
- What is the difference between a derived SI unit and a funda-mental SI unit? Give an example of each
- What type of quantity (for example, length, volume, density) do the following units indicate? (a) m3
- What type of quantity (for example, length, volume, density) do the following units indicate? (g) Pa.
- What type of quantity (for example, length, volume, density) do the following units indicate? (f) ms-1
- "Give the derived SI units for each of the following quantities in base SI units: (g) energy = mass * 1veloc...
- Give the derived SI units for each of the following quantities in base SI units: (e) power = work/time
- Give the derived SI units for each of the following quantities in base SI units: (a) acceleration = distance/t...
- Force is defined as mass times acceleration. Starting with SI base units, derive a unit for force. Using SI pr...