Chapter 1

Measurements

Units of Measurement

Measurement

You are making a measurement when you

Check you weight

Read your watch

Take your temperature

Weigh a cantaloupe

What kinds of measurements did you make today?

Standards of Measurement

When we measure, we use a measuring tool to compare some dimension of an object to a standard.

Stating a Measurement

In every measurement there is a

Number

followed by a

Unit from measuring device

Learning Check

What are some U.S. units that are used to measure each of the following?

A. length

B. volume

C. weight

D. temperature

Solution

Some possible answers are

A. length inch, foot, yard, mile

B. volume cup, teaspoon, gallon, pint,

C. weight ounce, pound (lb), ton

D. temperature F

Learning Check

What is the unit of measurement in each of the

following examples?

A. The patient’s temperature is 102°F.

B. The sack holds 5 lbs of potatoes.

C. It is 8 miles from your house to school.

D. The bottle holds 2 L of orange soda.

Solution

A. °F (degrees Fahrenheit)

B. lbs (pounds)

C. miles

D. L (liters)

Measurement in Science

In science we

do experiments

measure quantities

use numbers to report measurements

Metric System (SI)

Is a decimal system based on 10s Used in most of the world Used by scientists and many

business and organizations

Some Metric System Units

length meter m

volume liter L

mass gram g

temperatureCelsius °C

Learning Check

Identify the measurement in metric units.

A. John’s height is

1) 1.5 yards 2) 6 feet 3) 2 meters

B. The volume of saline in the IV bottle is

1) 1 liters 2) 1 quart 3) 2 pints

C. The mass of a lemon is

1) 12 ounces 2) 145 grams 3) 0.6 lbs

Solution

A. John’s height is

3) 2 meters

B. The volume of saline in the IV bottle is

1) 1 liter

C. The mass of a lemon is

2) 145 grams

Metric System Basics There is an established standard for

each type of measurement This unit does not have any prefix to it This unit is then divided by 10s into

smaller and smaller divisions Each of them has the appropriate prefix Example 1m = 10 smaller units each of

which is called a decimeter So what are the units and the prefixes

Metric Measurement Units Length = meter (m) Mass = gram (g) Volume = liter (L since lower case “L”

looks like a one and could be confusing) Time = second (s) Force = newton (N) Pressure = pascal (Pa) Energy = joule (J) Electric current = ampere (A)

Mnemonics

kangaroos

hop

down

mountains

drinking

chocolate

milk

Kahn’s hot dogs use dead cow meat

1st Letters Represent the Order of Metric Prefixes

k- = kilo- h- = hecto- da- = deka- m/u = meter/unit has no prefix

d- = deci- c- = centi- m- = milli-

Subdivisions of the Metric Units• When a meter is divided into 10 smaller units, each of them is called a decimeter• mathematically 1m = 10dm•but since a decimeter is smaller than a meter the portion of a meter that the decimeter represents is one-tenth, or 1dm = 0.1m•You need to be able to handle both