1. Understanding Standards of Measurement

2. Standards p. 14
Exact quantity that people agree to use to compare measurements
Ex.
1 foot = 12 in.
60 min = 1 hr.
60 sec = 1 min.
3 feet = 1 yard.

3. Universal Measurement Systems
Metric System is used everywhere in the world. Especially among the science community.
US wanted to be different from Europe and as a result adopted a different set of standards when they became an independent country.
Many people believe that one day we will switch back to the Metric System. (Most car speedometers have both Metric and US.

4. SI Prefixes p.15 SI Base Units Length = meter (m)
Mass = kilograms (kg)
Time = seconds (s)
Electric Current = Ampere (A)
Temperature = Kelvin (K)
Amount of Substance = mole (mol)
Intensity of light = candela (cd)
Common SI prefixes
Kilo- (k) = 1000 (base units)
Deci- (d) = 0.1 (base units)
Centi- (d) = 0.01 (base units)
Milli- (m) = (base units)
Micro- (μ) =
Nano- (n) =

5. How to remember? Kids Hate Deans Because Deans Call Mom Kilo - Hecto –
Deka –
Base Unit
deci-
centi –
milli-

6. Length
US – only us
We use metric
Metric – the rest of the world

7. Let’s Measure! 10.69 ± .01 cm What is the length of the bolt?
Rule: When Measuring you do what you know for sure + 1 estimated digit
Our Chance for Error!
What is the length of the bolt?
10.69 ± .01 cm
Each big number represents a cm
Our estimated digit

8. Let’s Practice! What is the width of the nut? 1.29 ± .01 cm
Our estimated digit
What is the width of the nut?
1.29 ± .01 cm
This would have 3 significant digits

9. What are significant digits (figures)?
Often called Significant Figures
a number are those digits that carry meaning contributing to its precision

10. Let’s Practice! What is the length of the of pencil? 8.65 ± .01 cm
This would have 3 significant digits
You can only get as precise as the instrument you are using.

11. Which devise is more Precise? Why?1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

12. Volume Use a graduated cylinder Units of measurements is liters(L)
What is the volume of the liquid?
This is where you measure
30.1 mL