Please show your work for the metric conversions below. 1) 45.72cm = _____ mm 2) 113.5 g = _____ kg 3) 220 mg = _____ g 4) 1x103mL = _____ L 5) 1x10-2m = _____ cm 6) 34 mm = _____ cm 7) 234 cm = _____ m 8) 4.7kg = _____g 9) 12345g = _____kg 10) 456cL = _____mL 11) 120mL = _____cm3 12) 52 hours = ______ μs 13) 57 oF = _______ oC

Measurement and Problem Solving Physics attempts to describe nature in an objective way through measurement.

SI Units of Length, Mass, and Time SI unit of length: the meter SI unit of mass: the kilogram SI 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 Metric Prefixes adjust units for a smaller or larger scale. You need to be able to use pico- through Giga- fluently.

Volume and Conversions The basic unit of volume in the SI system is the cubic meter Units of L and mL are more convenient for everyday use. 1 mL = cm3 How many centimeters are in one cubic meter?

Significant figures Meaningful digits in a MEASUREMENT Exact numbers are counted, have unlimited significant figures If 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 does Before the first number doesn’t After the last number counts if and only if… it is after the decimal point the decimal point is written in 3200 2 sig figs 3200. 4 sig figs

Doing the math Multiplication 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. 6.004 x 4.00 2.0 x 3.0 x 0.020 9.54 ÷ 0.808 1.040 ÷ 0.6040

Dimensional Analysis Use conversion factors to change the units 1 foot = 12 inches (equivalence statement) 12 in = 1 = 1 ft. 1 ft. 12 in 2 conversion factors to choose from multiply by the one that will give you the correct units in your answer.

Examples 11 yards = 2 rod 40 rods = 1 furlong 8 furlongs = 1 mile The Kentucky Derby race is 1.25 miles. How long is the race in rods, furlongs, meters, and kilometers? 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 light speed of light = 3.00 x 108 m/s 1 knot = 2000 yd/h exactly 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?

Examples 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 g 1 oz. ap = ? oz. troy What is the mass of 1 scruple in grams?

Examples 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 08/11/10 On the back of your homework, please complete the following unit conversions! 24 kilograms to centigrams 18.2 centimeters to hectometers 0.27 milliliters to centiliters 8.42 dekagrams to decigrams 7 decimeters to hectometers 6cg/DL to g/mL 2 mg/kL to cg/ML 9 ng/hL to Dg/cL 4 Gg to μg 8 g/kL to kg/dL BONUS 6 g to mL if the density is 12 g/mL

Problem Solving 1. 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 Homework P. 25-27, 3, 4, 7, 12, 26, 30, 45, 49 Parent Sign and Return Buy Supplies We will set up Lab Notebooks on 08/13! Make sure you are ready! Study for the Ch. 1 Quiz 08/13/09