1. Why? Because it makes sense!
Metric Conversions
Why? Because it makes sense!

2. Metric Prefixes
“Karen Has Damaged Many Little Gifts During Christmas Morning”
Kilo- 1000
Hecto- 100
Deca- 10
Base units: Meters (length), Liters (volume), Grams (mass) - 1
Deci- .1
Centi- .01
Mili- .001
Order of magnitude = power of ten (count the zeros)
Ex: 10 is one order of magnitude greater than 1
Ex: 1,000 is 2 orders of magnitude less than 100,000

3. Converting in the Metric System
Larger prefix – decimal moves left Smaller Prefix – decimal moves right 1 km = .62 mi 1 kg = 2.2 lbs 1 mL = 1 cm3 See handout – Copy into notebook/notes

4. Practice
Convert 75 mL to cm3 Convert 350 mL to L Convert 500 m to Km Convert Kg to g Convert 5.0 x 103 mL to L Convert 100 mL to L Convert 600 Kg to g Which two of these are equivalent lengths? 60 mm m 6000 cm Km In metric, the base unit for length is the ______. In the metric system, the base unit for mass is the ______. The measure of the amount of 3-D space that an object occupies is known as ________. Which of the following are equivalent lengths? 450 cm 45,000 mm 45 m 45,000 Km
Which of these is the shortest length?
60 mm Km
0.600 m 6000 cm
Which of the following is the largest mass?
1000 mg 5 Kg
800 cg 100 g
Which metric distance is equal to 0.62 miles?
1 mm 1 cm
1 Km 1 m
Which of the following conversions is/are incorrect?
1 Km = 1000 m 1 m = 1000 mm
500 cm = 0.5 m 100 mm = 1 cm
Which of the following metric masses is approximately equal to 2.2 pounds?
1 mg 1 Kg
1 µg 1 g 
How many millimeters are in one kilometer?
How many milliliters are in one deciliter?

5. How precisely can you measure?
Significant Figures
How precisely can you measure?

6. Precise vs. Accurate
Precise – how close are your measurements to each other?
Accurate – how close are your measurements to the correct measurement (truth)?

7. Significant figures
All digits in a measurement that are known for certain, plus the first estimated (uncertain) digit
Sig figs give an indication of the degree of precision for a measurement and/or calculation

8. Sig Fig rules – KNOW AND USE THEM
Rules for determining how many sig figs are in a measurement:
All non-zero values ARE significant
i.e. 54 mm has 2 sig figs
5400 m has 2 sig figs
All zeros between non-zero digits ARE significant
i.e. 504 N has 3 sig figs
For numbers less than 1
Zeros directly after the decimal point are not significant
i.e J has 3 sig figs

9. Sig Fig rules – KNOW AND USE THEM
Rules for determining how many sig figs are in a measurement: ctd
A zero to the right of a decimal AND following a non-zero digit IS significant
0.150 m has 3 s.f.
15.0 kg has 3 s.f.
All other zeros are NOT significant
If you wouldn’t write the zero in scientific notation, It’s not significant.

10. Scientific Notation & Sig Figs
Use scientific notation when you need to specify how many zeros are significant:
i.e. write 1500 N with 3 s.f.
The best way to do this is with scientific notation: 1.50 x 103 N
Write kg with 4 s.f.

11. Summary

12. Sig figs in problems
Many problems will have values that look like they only have 1 s.f.
Assume that all digits in the problems are significant
i.e. if a problem says that and object has a mass of 100 kg, please treat that as 3 s.f.

13. Sig. Figs in calculations
When adding/subtracting:
Your answer must have the same degree of precision as the least precise measurement (choose the smallest number of decimal places)
i.e.: 24.2 g g g = g →31.8 g
When multiplying/dividing:
The number of sig figs in the answer is equal to the least number of sig figs in any of the measurements used in the calculation
i.e.: 3.22 cm x cm x 1.8 cm = cm3 → 72 cm3

14. How many sig figs in each of the following?
Examples/ Homework
How many sig figs in each of the following?
415.2 cm s
1500 g W cm cm s
35000 kg
1.25 cm cm cm cm
2.32 mL mL mL mL
36.5 g g g
5.85 kg x kg x 7.3 kg
25.50 m x m x 0.095m
25.32 mL x 6.87 mL x 35.7 mL