Copyright 2013, 2010, 2007, Pearson, Education, Inc. Section 8.3 Mass and Temperature

Copyright 2013, 2010, 2007, Pearson, Education, Inc.

Section 8.3

Mass and Temperature


What You Will Learn

How to determine which unit of mass is appropriateConverting between Celsius and Fahrenheit

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Mass

Although weight and mass are not the same, on Earth they are proportional to each other.Mass is a measure of the amount of matter in an object. It does not vary. Weight is the measure of gravitational pull on an object. It varies.

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Gravitational PullThe gravitational pull of Earth is about six times as great as the gravitational pull of the moon.A person on the moon weighs about 1/6 as much as on Earth, even though the person’s mass remains the same.In space, where there is no gravity, a person has no weight but does have mass.

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Metric System

The kilogram is the basic unit of mass in the metric system.It is about 2.2 pounds.Kilogram is used to measure things that we normally measure in pounds.A man has a mass of about 75 kg.The gram is relatively small and used in place of the ounce. A nickel has the mass of about 5 g.

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Metric SystemThe milligram is used in the medical and scientific fields.Nearly all bottles of tablets are now labeled in either milligrams or grams.The metric tonne (t) is used to express mass of heavy items.One metric tonne equals 1000 kg.It is a little larger than our customary ton of 2000 lb.The mass of a large truck may be expressed in metric tonnes.

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Example 1: Choosing the Appropriate UnitDetermine which metric unit you would use to express the mass of the following.a) A 1-year-old child

Kilograms

b) A whaleMetric tonnes

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Example 1: Choosing the Appropriate Unitc) A pair of eyeglasses

Grams

d) A box of cerealGrams

e) A laptop computerGrams or kilograms

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Example 1: Choosing the Appropriate Unitf) A spider

Milligrams

g) A frogGrams

h) A refrigeratorKilograms

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Volume and Mass of WaterVolume in Cubic Units

1 m3 = 1 kl = 1 t (1000 kg)

1 dm3 = 1 l = 1 kg

1 cm3 = 1 ml = 1 g

Mass of Water

Volume in Liters

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Example 2: Volume of a Fish TankA fish tank is 1 m long, 50 cm high and 250 mm wide. a) Determine the number of liters that the tank holds.b) What is the mass of the water in kilograms?

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Solutiona) Convert measurements to meters50 cm = 0.5 m, 250 mm = 0.25 m

V = l × w × h = 1 × 0.25 × 0.5 = 0.125 m3

Since 1 m3 of water = 1 kl of water,0.125 m3 = 0.125 kl, or 125 l of waterb) Since 1l = 1 kg, 125 l = 125 kgThe water in the fish tank has a mass of 125 kg.

Example 2: Volume of a Fish Tank

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TemperatureThe Celsius scale is used to measure temperatures in the metric system.The figure shows a thermometer with the Fahrenheit scale on the left and the Celsius scale on the right.On the Celsius scale, water freezes at 0ºC and boils at 100ºC.

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TemperatureSome common temperatures in both degrees Celsius (ºC) and degrees Fahrenheit.

Mild spring day68ºF20ºCWarm winter day50ºF10ºC

Freezing point of water

32ºF0ºCVery cold day0ºF–18ºCDescriptionºFºC

Temperature

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Temperature

Oven temperature for baking

351ºF177ºCBoiling point of water

212ºF100ºC

Body temperature98.6ºF37ºCWarm summer day86ºF30ºCDescriptionºFºC

Temperature

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Example 3: MetricTemperaturesChoose the best answer.

a) Chicago, Illinois, on New Year’s Day might have a temperature of

–10ºC 20ºC 45ºC

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b) Washington, D.C., on July 4 might have a temperature of

15ºC 30ºC 40ºC

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c) The oven temperature for baking a cake might be

60ºC 100ºC 175ºC

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Conversions

Celsius to Fahrenheit

Fahrenheitto Celsius

F

9

5C 32

C

5

9F 32

To convert from

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Example 4: Convert to ºCA typical setting for home thermostats is 72°F. What is the equivalent temperature on the Celsius thermometer?

SolutionSubstitute F = 72 into

C

5

9F 32

C

5

972 32

5

940 22.2º C

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Example 5: Convert to ºFIf the temperature outdoors is 28°C, what is the temperature in degrees Fahrenheit?

SolutionSubstitute F = 72 into

F

9

5C 32

F

9

528 32 50.432 82.4ºF

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Documents

Copyright 2013, 2010, 2007, Pearson, Education, Inc. Section 8.3 Mass and Temperature