1) 45.72cm = _____ mm2) 113.5 g = _____ kg3) 220 mg = _____ g4) 1x103mL = _____ L5) 1x10-2m = _____ cm6) 34 mm = _____ cm7) 234 cm = _____ m8) 4.7kg = _____g9) 12345g = _____kg10) 456cL = _____mL11) 120mL = _____cm3

12) 52 hours = ______ μs13) 57 oF = _______ oC

Please show your work for the metric conversions below.

Measurement and Problem SolvingPhysics attempts to describe

nature in an objective way

through measurement.

SI Units of Length, Mass, and Time

SI unit of length: the meterSI unit of mass: the kilogramSI unit of time: the second

Seven units are believed to be all that are necessary to describe all phenomena in nature.

Metric Prefixes adjust units for a smaller or larger scale. You need to be able to use pico- through Giga- fluently.

Volume and ConversionsThe basic unit of volume in the SI

system is the cubic meterUnits of L and mL are more

convenient for everyday use.1 mL = cm3

How many centimeters are in one cubic meter?

Significant figuresMeaningful digits in a MEASUREMENTExact numbers are counted, have

unlimited significant figuresIf it is measured or estimated, it has

sig figs.If not it is exact.All numbers except zero are

significant.Some zeros are, some aren’t

Which zeroes count?In between other sig figs doesBefore the first number doesn’tAfter the last number counts if and

only if…it is after the decimal pointthe decimal point is written in3200 2 sig figs3200. 4 sig figs

Doing the mathMultiplication and division, same

number of sig figs in answer as the least in the problem

Addition and subtraction, same number of decimal places in answer as least in problem.

1. 6.004 x 4.002. 2.0 x 3.0 x 0.0203. 9.54 ÷ 0.8084. 1.040 ÷ 0.60405. 6.

Dimensional Analysis

Use conversion factors to change the unitsConversion factors = 11 foot = 12 inches (equivalence statement)12 in = 1 = 1 ft.

1 ft. 12 in

2 conversion factors to choose frommultiply by the one that will give you the

correct units in your answer.

Examples

11 yards = 2 rod40 rods = 1 furlong8 furlongs = 1 mile1. The Kentucky Derby race is 1.25

miles. How long is the race in rods, furlongs, meters, and kilometers?

2. A marathon race is 26 miles, 385 yards. What is this distance in rods, furlongs, meters, and kilometers?

Examples

Warp 1.71 = 5.00 times the speed of lightspeed of light = 3.00 x 108 m/s1 knot = 2000 yd/h exactly3. Science fiction often uses nautical

analogies to describe space travel. If the starship U.S.S. Enterprise is traveling at warp factor 1.71, what is its speed in knots?

Apothecaries (druggists) use the following set of measures in the English system:

20 grains ap = 1 scruple (exact)3 scruples = 1 dram ap (exact)8 dram ap = 1 oz. ap (exact)1 dram ap = 3.888 g1 oz. ap = ? oz. troy4. What is the mass of 1 scruple in

grams?

Examples

Examples

5. The speed of light is 3.00 x 108 m/s. How far will a beam of light travel in 1.00 ns?

Warm-Up 08/11/10On the back of your homework, please complete the following unit conversions!1. 24 kilograms to

centigrams

2. 18.2 centimeters to hectometers

3. 0.27 milliliters to centiliters

4. 8.42 dekagrams to decigrams

5. 7 decimeters to hectometers

6. 6cg/DL to g/mL

7. 2 mg/kL to cg/ML

8. 9 ng/hL to Dg/cL

9. 4 Gg to μg

10.8 g/kL to kg/dL

BONUS

6 g to mL if the density is 12 g/mL

Problem Solving1. Read the problem carefully and

analyze it.

2. Draw a sketch or diagram of the problem.

3. Write down the given data and what is to be found. (Make unit conversions if necessary.)

4. Determine which principle(s) are applicable.

5. Perform calculations with given data.

6. Consider if the results are reasonable.

7. Make sure answers include units and/or labels.

Tonight’s HomeworkP. 25-27, 3, 4, 7, 12, 26, 30, 45, 49Parent Sign and ReturnBuy SuppliesWe will set up Lab Notebooks on

08/13! Make sure you are ready!Study for the Ch. 1 Quiz 08/13/09