9.3 Measuring Weight and Temperature

Weight and Mass Mass --the measure of quantity of matter in an object; the larger the mass, harder to change its speed Weight --the measure of the gravitational pull on an object; proportional to mass In this section we will deal exclusively with weight.

Units of Weight English System 16 ounces (oz) = 1 pound (lb) 2000 pounds (lb) = 1 ton (T) Metric System 1 kilogram (kg) = 1000 grams (g) 1 milligram (mg) = gram Conversion 1 kg ≈ 2.2 lb 1 lb ≈ 454 g E.g.: A sumo wrestler weighs 200 kg. What is his weight in pounds? 200 kg = 200 x 1 kg = 200 x 2.2 lb = 440 lb

Your Turn Given: 16 oz = 1 lb; 2000 lb = 1 T 1 kg = 1000 g; 1 mg = gram 1 kg ≈ 2.2 lb; 1 lb ≈ 454 g How many grams is 950 mg? 950 mg = 950 x 1 mg = 950 x 10-3 g = 0.95 g. How many kilograms is 180 lb? 180 lb = 180 x 1 lb = 180 x (1 kg/2.2) ≈ 81.8 kg How many grams is a quarter-pounder hamburger? (1/4)lb = (1/4) x 1 lb = (1/4) x 454 g ≈ 113 g

Temperature Measurement Fahrenheit temperature scale Water freezes at 32 degrees F (32° F) Water boils at 212 degrees F (212 ° F) Originally: Lowest temperature reached with brine--0 ° F Human temperature--100 ° F Celsius temperature scale Water freezes at 0 degrees C (0° C) Water boils at 100 degrees C (100° C) Absolute temperature scale Absolute 0: ° C or ° F

Comparing Temperature Scales

Converting Temperatures From Celsius to Fahrenheit F = (9/5)C + 32 E.g.: What is the 20 °C room temperature in Fahrenheit? F = (9/5)C + 32 = (9/5)(20) + 32 = 68 From Fahrenheit to Celsius C = (5/9)(F – 32) E.g.: What is the human body temperature (98 °F) in Celsius? C = (5/9)(F – 32) = (5/9)(98 – 32) = (5/9)(66) ≈ 36.7

Your Turn For humans, normal temperature is between 97.7 °F and 99.5 °F. Temperatures between 99.5 °F and 109 °F is considered feverish. Your Italian who arrived on an overnight flight has a temperature of 39.5 °C. Should you panic? Solution: F = (9/5)C + 32 = (9/5) = 103.1