MeasurementUnit 1 Ch 1.3 Ppt

Using Scientific Notation Scientific Notation is a way of

expressing a value as the product of a number between 1 and 10 and a power of 10.

Scientific Notation makes very large or very small numbers easier to work with.

Scientific Notation

Example: The number 300,000,000 written in scientific notation is 3.0x108. The exponent, 8, tells you that the decimal point is really 8 places to the right of the 3.

Example: The number 0.00086 written in scientific notation is 8.6x10-4. The negative exponent, -4, tell you that the decimal point is really 4 places to the left of the 8.6.

Multiplication & Division

When multiplying numbers written in scientific notation, you multiply the numbers that appear before the multiplication signs and add the exponents.

When dividing numbers written in scientific notation, you divide the numbers that appears before the exponential terms and subtract the exponents.

Example: 3.0x108 x 5.0x102 = 15x1010 = 1.5x1011

Example: 1.5x1011 = 1.5x 1011-8 = 0.5x103 =5.0x102

3.0x108 3.0

Multiplication & Division

SI Units of Measurements

International System of Units SI is built upon seven metric units,

known as Base Units.› Example: The base unit for length(L) is the

meter (m). Additional SI units, called Derived

Units, are from combinations of base units.› Example: The derived unit for volume (V) is

cubic meters (m3).

SI Base UnitsQuantity Unit Symbol

Length Meter M

Mass Kilogram Kg

Temperature Kelvin K

Time Second S

Amount of substance Mole Mol

Electric current Ampere A

Luminous intensity Candela cd

Derived Units

Quantity Unit Symbol

Area Square meter M2

Volume Cubic meter M3

Density Kilograms per cubic meter

Kg/m3

Pressure Pascal (kg/mxs2) Pa

Energy Joule (kgxm2/s2) J

Frequency Hertz (1/s) Hz

Electric Charge Coulomb (Axs) C

Metric Prefixes

Prefix Symbol Meaning Multiply Unit by

Giga- G Billion 1,000,000,000

Mega- M Million 1,000,000

Kilo- k Thousand 1,000

Deci- d Tenth 0.1

Centi- c Hundreth 0.01

Milli- m Thousandth 0.001

Micro- µ Millionth 0.000001

Nano- n Billionth 0.000000001

Conversion Factor

A conversion factor is a ratio of equivalent measurements that is used to convert a quantity expressed in one unit to another unit.

Example: Convert the height of Mt. Everest, 8848 meters, into kilometers. kilo-=1000

8848m X 1km = 8.848km 1000m

Limits of Measurements

Precision is a gauge of how exact a measurement is.

Precision of a calculated answer is limited by the least precise measurement used in the calculation.

Accuracy is the closeness of a measurement to the actual value of what is being measured.

Limits of Measurement

Significant figures are all the digits that are known is a measurement, plus the last digit that is estimated.› Example: On an analog clock it may take

you 5 minutes to eat a sandwich. On a digital clock it may take you 5.25 minutes to eat a sandwich. The time recorded as 5.25 minutes has three significant figures. The time recorded as 5 minutes has one significant figure. The fewer the significant figures, the less precise the measurement.

Measuring Temperature

A thermometer is an instrument that measures temperature, or how hot an object is.

The two temperature scales that you are probably most familiar with are the Fahrenheit scale and the Celsius scale.

Fahrenheit: water freezes at 32 degrees Celsius: water freezes at 0 degrees Conversion:

ºC = 5 (ºF – 32.0º) or ºF = 9 (ºC) +32.0º

9 5

Measuring Temperature

SI unit for temperature is kelvin (K).

Conversion:K = ºC + 273

Homework

Textbook:› Section 1.3 Assessment (page 20)› Questions 1 – 6

Workbook:› Section 1.3 Measurement (pages 7-8)