CH1010 Lecture 2

9mmby111mmby119mmwhat isthedensityofliingcm3 plan

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Unformatted text preview: ally you have to find the length of the 1 km = 103 m entire cable and convert it to mass. length (m) of fiber SOLUTION: 103 m 8.84 x 10 km x km 3 6 = 8.84 x 106 m 1 m = 1.19x10­3 lb mass (lb) of fiber 6 fibers = 1 cable mass (lb) of cable 2.205 lb = 1 kg mass (kg) of cable 1.19 x 10 ­3 lbs 8.84 x 10 m x = 1.05 x 104 lb m 6 fibers = 1.05 x 104 lb x cable cable 6.30 x 104 lb cable 1kg 6.30 x 104 lb 2.86 x 104 kg x = cable 2.205 lb Sample Problem 1.6 Calculating Density from Mass and Length PROBLEM: If a rectangular slab of Lithium (Li) weighs 1.49 x 103 mg and has sides that measure 20.9 mm by 11.1 mm by 11.9 mm, what is the density of Li in g/cm3 ? PLAN: Density is expressed in g/cm3 so we need the mass in grams and the volume in cm3. mass (mg) of Li 103 mg = 1 g mass (g) of Li lengths (mm) of sides 10 mm = 1 cm 1 g = 1.49 g 1000 mg = 2.09 cm lengths (cm) of sides multiply lengths volume (cm3) divide mass by volume density (g/cm3) of Li 1.49 g 2.76 cm3 SOLUTION: 1.49x103 mg x 20.9 mm x 1 cm 10 mm Similarly the other sides will be 1.11 cm and 1.19 cm, respectively. 2.09 x 1.11 x 1.19 = 2.76 cm3 density of Li = = 0.540 g/cm3 Sample Problem 1.7 Converting Units of Temperature PROBLEM: A child has a body temperature of 38.7°C. (a) If normal body temperature is 98.6°F, does the child have a fever? (b) What is the child’s temperature in kelvins? PLAN: We have to convert °C to °F to find out if the child has a fever and we use the °C to Kelvin relationship to find the temperature in Kelvin. 9 5 SOLUTION: (a) Converting from °C to °F (b) Converting from °C to K (38.7°C) + 32 = 101.7°F 38.7°C + 273.15 = 311.8K Sample Problem 1.8 Determining the Number of Significant Figures PROBLEM: For each of the following quantities, underline the zeros that are significant figures (sf), and determine the number of significant figures in each quantity. For (d) to (f), express each in exponential notation first. (a) 0.0030 L (d) 0.00004715 m PLAN: (b) 0.1044 g (e) 57,600. s (c) 53,069 mL (f) 0.0000007160 cm3 Determine the number of sf by counting digits and paying att...
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