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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. Quantity. Base Unit. Symbol. Length. meter. m. Mass. kilogram. kg. Time. second.
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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 Quantity Base Unit Symbol Length meter m Mass kilogram kg Time second s Temp kelvin K Current ampere A
SI Units continued… Force Weight Velocity Acceleration Light N N m/s m/s2 cd Newtons Newtons (due to gravity) Distanceper time Distance per time2 Candela
mega- kilo- M k 103 106 deci- d 10-1 centi- c 10-2 milli- m 10-3 micro- 10-6 nano- n 10-9 pico- p 10-12 B. SI Units Prefix Symbol Factor
M V M D = D V C. Derived Units • Combination of base units. • Volume - length length length 1 cm3 = 1 mL 1 dm3 = 1 L • Density - mass per unit volume (g/cm3)
M D V D. Density • An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: V = 825 cm3 D = 13.6 g/cm3 M = ? WORK: M = DV M = (13.6 g/cm3)(825cm3) M = 11,220 g
WORK: V = M D V = 25 g 0.87 g/mL M D 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 V = 28.74 mL
WORK: D = M V D = 620 g 753 cm3 M D V D. Density 2) You have a sample with a mass of 620 g & a volume of 753 cm3. Find density. GIVEN: M = 620 g V = 753 cm3 D = ? D = 0.82 g/cm3
To the left or right? A. SI Prefix Conversions 1. Find the difference between the exponents of the two prefixes. 2. Move the decimal that many places.
NUMBER = UNIT A. SI Prefix Conversions 0.532 532 m = _______ km NUMBER UNIT
kilo- mega- M k 106 103 deci- d 10-1 centi- c 10-2 milli- m 10-3 micro- 10-6 nano- n 10-9 pico- p 10-12 A. SI Prefix Conversions Prefix Symbol Factor move left move right
1) 20 cm = ______________ m 2) 0.032 A = ______________ mA 3) 45 m = ______________ nm 4) 805 dm = ______________ km A. SI Prefix Conversions 0.2 32 45,000 0.0805
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 1 in = 2.54 cm 2.54 cm 2.54 cm 1 = 1 in = 2.54 cm 1 in 1 in
cm in B. Dimensional Analysis • Your European hairdresser wants to cut your hair 8 cm shorter. How many inches will he be cutting off? 8 cm 1 in 2.54 cm = 3.15 in
qt mL B. Dimensional Analysis • How many milliliters are in 1 quart of milk? 1 L 1.057 qt 1000 mL 1 L 1 qt = 946 mL
kg lb B. Dimensional Analysis 5) Assume your mass is 55 kg. How many pounds do you weigh? 55 kg 2.2 lb 1 kg = 121 lb
km ft B. Dimensional Analysis 6) How many feet long is a 5K (5 km) race? 1 mi 1.609 km 5280 ft 1 mi 5 km = 16,408 ft
lb g B. Dimensional Analysis 7) How many grams does a 10-lb. bag of potatoes weigh? 1 kg 2.2. lb 1000 g 1 kg 10 lb = 4545 g
cm yd B. Dimensional Analysis 8) Taft football needs 550 cm for a 1st down. How many yards is this? 1 ft 12 in 1 yd 3 ft 1 in 2.54 cm 550 cm = 6.01 yd