Measurement I. Units of Measurement  Number vs. Quantity  SI Base Units & Prefixes  Derived Units  Density Calculations

A. Number vs. Quantity  Quantity - number + unit UNITS MATTER!!

B. SI Units QuantityBase UnitSymbol Length Mass Time Temp meter kilogram second kelvin m kg s K CurrentampereA

SI Units continued… Force Weight Velocity Acceleration Light Newtons Newtons (due to gravity) Distance per time Distance per time 2 Candela N N m/s m/s 2 cd

B. SI Units mega-M10 6 deci-d10 -1 centi-c10 -2 milli-m10 -3 PrefixSymbolFactor micro-  nano-n10 -9 pico-p kilo-k10 3

C. Derived Units  Combination of base units.  Volume - length  length  length 1 cm 3 = 1 mL 1 dm 3 = 1 L  Density - mass per unit volume (g/cm 3 ) D = MVMV D M V

D. Density  An object has a volume of 825 cm 3 and a density of 13.6 g/cm 3. Find its mass. GIVEN: V = 825 cm 3 D = 13.6 g/cm 3 M = ? WORK : M = DV M = (13.6 g/cm 3 )(825cm 3 ) M = 11,220 g D M V

D. Density 1) A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? M = 25 g D M V WORK : V = M D V = 25 g 0.87 g/mL V = mL

D. Density 2) You have a sample with a mass of 620 g & a volume of 753 cm 3. Find density. GIVEN: M = 620 g V = 753 cm 3 D = ? D M V WORK : D = M V D = 620 g 753 cm 3 D = 0.82 g/cm 3

A. SI Prefix Conversions 1. Find the difference between the exponents of the two prefixes. 2. Move the decimal that many places. To the left or right?

= A. SI Prefix Conversions NUMBER UNIT NUMBER UNIT 532 m = _______ km 0.532

A. SI Prefix Conversions mega-M10 6 deci-d10 -1 centi-c10 -2 milli-m10 -3 PrefixSymbolFactor micro-  nano-n10 -9 pico-p kilo-k10 3 move left move right

A. SI Prefix Conversions 1) 20 cm = ______________ m 2) A = ______________ mA 3) 45  m = ______________ nm 4) 805 dm = ______________ km ,000 32

B. Dimensional Analysis  The “Factor-Label” Method  Units, or “labels” are canceled, or “factored” out

B. Dimensional Analysis  Steps: 1. Identify starting & ending units. 2. Line up conversion factors so units cancel. 3. Multiply all top numbers & divide by each bottom number. 4. Check units & answer.

B. Dimensional Analysis  Lining up conversion factors: 1 in = 2.54 cm 2.54 cm 1 in = 2.54 cm 1 in 1 in = 1 1 =

B. Dimensional Analysis  Your European hairdresser wants to cut your hair 8 cm shorter. How many inches will he be cutting off? 8 cm1 in 2.54 cm = 3.15 in  cmin

B. Dimensional Analysis  How many milliliters are in 1 quart of milk? 1 qt 1 L qt = 946 mL qtmL 1000 mL 1 L

B. Dimensional Analysis 5) Assume your mass is 55 kg. How many pounds do you weigh? 55 kg2.2 lb 1 kg = 121 lb kglb

B. Dimensional Analysis 6) How many feet long is a 5K (5 km) race? 5 km 1 mi km = 16,408 ft kmft 5280 ft 1 mi

B. Dimensional Analysis 7) How many grams does a 10-lb. bag of potatoes weigh? 10 lb 1 kg 2.2. lb = 4545 g lbg 1000 g 1 kg

B. Dimensional Analysis 8) Taft football needs 550 cm for a 1st down. How many yards is this? 550 cm 1 in 2.54 cm = 6.01 yd cmyd 1 ft 12 in 1 yd 3 ft