Lab One: Measurement and Metric Conversions

Metric System

The metric system is a decimalized system of measurement.

Metric System

Since the 1960s the International System of Units ("Système International d'Unités" in French, hence "SI") has been the internationally recognized standard metric system.

Metric units are widely used around the world for personal, commercial and scientific purposes.

Metric System

A standard set of prefixes in multiples of ten may be used to derive larger and smaller units.

Metric System

The Metric and Customary Systems of Measurement

In today’s global environment, metric measurements are prominent in workplaces, consumer products, and news reports.

Almost every other country in the world uses the metric system of measurement.

Three nations have not officially adopted the International System of Units as their primary or sole system of measurement: Burma, Liberia, and the United States.

The European Union, Japan, and Korea have passed legislation limiting international commerce to products measured in metric units.

Countries by Date of Metrication

If the United States is to continue to play a leading role in international business, using metric measurement is imperative and U.S. workers at all levels must be knowledgeable about the Système Internationale (SI), the international name for the metric system.

The Metric and Customary Systems of Measurement

Cargo errors - The confusion between pounds (mass) and kilograms sometimes means that aircrafts are overloaded. "the shipper's weights had been in kilograms, not pounds, and that, as a result, the aircraft was more than 30,000 pounds overweight".

Importance of Conversion…

Importance of Conversion…

Gimli Glider — In 1983 a Boeing 767 jet ran out of fuel in mid-flight because of two mistakes in figuring the fuel supply of Air Canada's first aircraft to use metric measurements.

Medical errors - Medical errors in the US are sometimes attributed to the confusion between grains and grams. A patient received phenobarbital 0.5 grams instead of 0.5 grains (0.03 grams) after the prescriber misread the prescription.

Importance of Conversion…

Mars Climate Orbiter — In 1999 NASA lost a $125 million Mars orbiter because one engineering team used metric units while another used US customary units for a calculation.

Importance of Conversion…

Metric System

• One of the goals of the metric system is to have a single unit for any physical quantity.

• Another important one is not needing conversion factors when making calculations with physical quantities.

Metric System

• All lengths and distances are measured in meters, or thousandths of a meter (millimeters), or thousands of meters (kilometers), and so on.

Metric System

• There are not different units with different conversion factors, such as inches, feet, yards, fathoms, rods, chains, furlongs, miles, nautical miles, leagues, etc.

Metric System

• Multiples and submultiples are related to the fundamental unit by factors of powers of ten, so that one can convert by simply moving the decimal place: 1.234 meters is 1234 millimeters, 0.001234 kilometers, etc. – The use of fractions, such as 2⁄7 of a meter, is not

prohibited, but uncommon, as it is generally not necessary.

Metric System

• The US uses the English System of measurement.– Not even the

English use the English system anymore.

Metric System

Metric System

• The rest of the world, especially scientists, use the metric system, or System International (SI).

• Since we are in the US, your lab manual uses both systems.– We need to be familiar and comfortable using both

systems.– We also need to be able to convert units from one

system to another.

Measurement and Metric Conversions

You will work with topographic maps You will have to measure distance Answers will be based on distance you measure

Objective: learn good techniques first

You will be measuring in inches and centimeters

You will need to convert to useful units like feet

and meters and miles or kilometers

Measurement and Metric Conversions

You will also need to convert from the English system of measurement to the System International or the Metric System and from SI to English.

Measurement and Metric Conversions

Materials

RulerCalculator

Objectives

• Practice measuring• Practice converting within a system• Practice converting between systems• Practice rounding

Measuring Distance

Rulers have inches and centimetersInches are divided into 16ths Centimeters are divided into 10ths, which are mi

llimetersSee the first picture• A 6/16• B 12/16• C 5/10• D 2 cm or 20 mm

Converting Fractions into Decimals

Divide the numerator (top number) into the denominator (bottom number)

When we measure, we get fractions, but when we have to work with our measurements, like conversions, it is easier to work with decimals.

Problem 1

Measure lines 1, 2, and 3Express your measured distance as a fraction, the

n convert your answer to a decimal.

Problem 2

Measure lines 4, 5, and 6Express your answers first in fractions of centim

eters, then convert to a decimal, and finally express your answer in millimeters.

Converting Units of Measurement

Multiply original unit of measure by conversion factor.

1 foot =12 inchesSo5 feet X 12 = 60 inches

Conversion Factors

1 foot = 12 inches1 mile = 5,280 feet = 63,360 inches1 gallon = 4 quarts

1 meter = 100 centimeters = 1,000 millimeters1 kilometer = 1,000 meters1 kilometer = 100,000 centimeters = 1,000,000

millimeters

Problems 3 - 10

Convert measurements within systems

Conversion Factors

1 mile = 1.6 kilometers1 kilometer = .621 miles

1 kilogram = 2.205 pounds1 pound = .454 kilograms

1 liter = 1.057 quarts1 quart = .946 liters

Temperature Conversions

Use the following formulas to make conversions between Celsius and Fahrenheit

F = (C × 1.8) + 32C = (F – 32) ÷ 1.8

Problems 11 - 20

Convert between systemsUse conversion factorsUse temperature conversion formulas

Precision and Rounding

Rule for geography lab:Always round to the nearest tenth, or one decima

l place. Why? Because we cannot be more precise than 1/10 of

a centimeter.

Problems 21 - 34 (30)

Round numbers to the nearest tenth, hundredth, and whole number.

Precision and Rounding

Rule for geography lab:Always round to the nearest tenth, or one decima

l place. Why? Because we cannot be more precise than 1/10 of

a centimeter.

Rounding

• Often numbers are not exact• Is 3.2571429 correct or useful number?

Rounding

• No… – It is usually implied that the greater number of

digits more precise.• Not always

– Distance measurement is only accurate to tenths of centimeters, so a final answer should be no than one decimal point.

Rounding

Rounding

• If the first digit to be dropped is less than 5, leave the preceding digit.

• If the digit is greater than 5, increase the preceding digit by one.– Example: 6.74 = 6.7

• Example: 6.75 = 6.8