Measurement

Measurement

• Measurements have 2 parts:– A number– A unit

• Example: 5cm

• Scientists (and we will) use the SI system– Système International d’unités

The SI units = METRIC

• There are only 3 countries in the whole world using the ENGLISH SYSTEM of measurement– Liberia– Myanmar (formerly Burma)– THE UNITED STATES of AMERICA

• Why is the metric system so much easier?– Most countries use it– It is based on powers of 10

Units

• There is always a BASE unit for every measurement

• There can be prefixes added to the base to make it larger or smaller

Example: millisecond, kilogram

Base Units

• Length = meter (m)• Mass = gram (g)• Volume = liter (L) or cubic centimeters (cm3)• Time = second (s)

** Prefixes multiply the BASE unit by a value of 10 **

Kilo k 1,000 hecto h 100deka da 10base: 1deci d 0.1centi c 0.01milli m 0.001

PREFIX Symbol multiplier

King Henry Died

UnfortunatelyDrinking

ChocolateMilk

Unit Conversions

• The metric system is so useful because we can convert from one unit to another EASILY

1. Write out the abbreviations in a horizontal row: K H D U D C M

2. Find the location of the original unit, then count the number of jumps and direction to the new unit

3. Re-write the number, then hold the pencil on the decimal point.

4. Move your pencil, making “egg crates”, the number of jumps in the correct direction- then fill in the empy crates with ZEROS

5. Re-write your final answer, including number and unit

Let’s try some!

Convert:12 gram to kilograms87.25 hL to cL5.22 seconds to milliseconds99.99 dm to cm

How many centiliters are in 1 kiloliter?

Length

• Length = distance from one point to another• Length is measured with a METRIC RULER• The BASE unit = meter

• Examples: centimeter (cm), millimeter (mm), decimeter (dm)

Mass

• Mass= the amount of matter in an object• Mass is measured with a balance• The BASE unit = gram

• Examples: kilogram (kg), milligram (mg)

Volume

Solid Measurement• The BASE unit = cm3

• Use a formula to calculate for regular shapes

• For irregular shapes use Water Displacement Method

Liquid Measurement• The BASE unit = Liter• Use a GRADUATED

CYLINDER to measure

Volume= the amount of space something takes up

Volume

Direct Measurement• Use a ruler to measure and

plug into formula

• Example: Volume of a cube = length x width x height

Indirect Measurement• Water displacement

method1. Fill a graduated cylinder

with water- record volume2. Carefully add object-

record new volume of water

3. Subtract old volume from new volume = volume of object

In order for a measurement to be reliable…

It needs to be both ACCURATE and PRECISE

• Accuracy = EXACT • Precision = multiple measurements close to

each other

Scientific Notation

• Makes using large numbers easier• Write a number times a power of 10

• Example:• 3.0 x 108 = 300,000,000• Number must be between 1 and 10• Always there• The NUMBER of places and DIRECTION the

decimal is moved

Scientific Notation

• #’s less than 1 (0.30400823) have a NEGATIVE exponent

• #’s greater than 1 have a POSITIVE exponent

Try Some:

• Expand:

• 4.2 x 104

• 3.359 x 10 -6

• 7.8112 x 108

Try Some More…

• Write in scientific notation:

• 870• 0.0000789• 0.245• 75000