metric and measurement notes. seven basic measurement areas (metric units)

Metric and Metric and Measurement Measurement

NotesNotes

Seven Basic Measurement Areas

(Metric Units)

Length

• The basic unit of measurement for length is a: meter.

• The instrument used is a:meter stick.

Standard: distance light travels in 1/2.9979x108 seconds or 3.3x10-9 seconds

Mass• The basic unit of measurement for mass

is a: gram.

• The instrument used is a:triple beam balance.

Standard: plantinum iridium cylinder – stored in a vault in the International Bureau of Weights and Measurements in France

Mass vs Weight

• Mass – amount of particles (atoms) a substance contains

• Weight – force of gravity pulling on an object

Time

• The basic unit of measurement for time is a: second.

• The instrument used is a: stopwatch

Standard: 9x109 vibrations of Cesium 133

Temperature

• The basic unit of measurement for temperature is: Celsius (or Kelvin). 0°C (freezing) . . . . . . . . . . . . . 100°C (boiling)

• The instrument used is a:thermometer.

Standard: the triple point of water – the temperature and pressure at which solid, liquid and vapor are all present = 273.16K or 0.01C

Amount of a Substance

• The basic unit of measurement for the amount of a substance is:a mole

• Avogadro’s number: 6.022x1023

Standard: the amount of substance containing the same number of particles as 12.00g of carbon 12

Light Intensity

• The basic unit of measurement for light intensity is:candela (cd)

• The instrument used is a:spectrophotometer

Original definition: the amount of light emitted by a common candle.

Standard: intensity of a source that emits a monochromatic light of 540x1012Hz with an intensity of 1/683 steradians

Electrical Current • The basic unit of measurement for

electrical current is:Ampere (A)

• The instrument used is an:amp meter

Standard: the amount of electrical charge passing a point in an electrical circuit per unit time with 6.241x1018 electrons OR a force of 2x10-7N/m between 2 parallel conductors of infinite length of negligible cross section in a vacuum

Derived Units

• Units that are formed by any combination of basic units:– Area (l x w)– Volume (l x w x h)– Density (m/v)– Force (N = kgm/s2)

Volume

• The basic unit of measurement for volume is a: liter.

• The instrument used is a:graduated cylinder.

Measure the volume of liquid at the bottom of the meniscus.

NEVER use a beaker for measuring volume, it is not accurate.

Volume (cont.)

To measure the volume of a regularly shaped solid, multiply:

length x width x height

Basic unit of volume for a solid: m3

Density (cont.)

• Equation: mass/volume• Basic unit of measurement of

density:Solid: g/m3

Liquid: g/L

Metric System

The metric system is based on the number 10 and multiples of 10.

kilo hecta deca basic deci centi milli

k h dk d c m

1000 100 10 1 0.1 0.01 0.001

or or or 1/10 1/100 1/1000

Additional Metric Prefixes

• Tera 1012

• Giga 109

• Mega 106

• Kilo 103

• centi 10-2

• mili 10-3

• micro (μ) 10-6

• nano (n) 10-9

Approximations and Conversions

• 1 m ≈ 1 yard 1 in = 2.540 cm

• 1 L ≈ 1 quart 1 qt = .9463 L• 1Kg ≈ 2 lb 1 lb = 453.6g

1 mile = 1.609 Km