SECTION 2.1THE MEASURES OF SCIENCE

2.1 THE MEASURES OF SCIENCEJournal Entry #1

Develop and write a plan to determine the answer to the following question…

How many drops of water will it take to fill the bucket?

Materials: Colored water, eye dropper, graduated cylinder, meter stick

2.1 THE MEASURES OF SCIENCEObjectives

Define the SI standards of measurement

Use common metric prefixes Estimate measurements and solutions

to problems Perform arithmetic operations using

scientific notation

2.1 THE MEASURES OF SCIENCE

We gotta have standards!!!

2.1 THE MEASURES OF SCIENCEThe Metric System and SI

The Metric System was adopted by French scientists in 1795.

Prior to the adoption of the Metric System, units of measurement were not standardized, but based on local customs.

The Metric System provided a standard system that was in an easy to use, base ten system.

2.1 THE MEASURES OF SCIENCE The system currently in use by most of

the scientific community is an adaptation of the Metric System called SI (Systeme Internationale d’Unites).

SI is regulated by an international organization.

The standards of length, time, and mass are kept in France and Maryland.

2.1 THE MEASURES OF SCIENCE Countries not yet using metric system….

US, Liberia, Myanmar

2.1 THE MEASURES OF SCIENCESI Base Units

SI Base Units

Base Quantity Base Unit Symbol

Length meter m

Mass kilogram kg

Time second s

Temperature kelvin KAmount of a substance mole mol

Electric current ampere A

Luminous intensity candela cd

2.1 THE MEASURES OF SCIENCE The base units are defined based on

some fixed standards. SI also recognizes derived units, which

are combinations of the base units (ex. – m/s for speed, and kg*m2/s2)

As you get more familiar with the derived units, you will be able to use something called dimensional analysis to help ensure the accuracy of your answers.

2.1 THE MEASURES OF SCIENCE

2.1 THE MEASURES OF SCIENCE Scientific notation is writing numbers as a

number times a power of ten. Numbers in scientific notation are always in

the form Mx10n where 1≤M<10 and n is an integer.

To express a number in scientific notation, move the decimal point so there is one non-zero digit to the left of the decimal.

Next, count the number of places you moved the decimal and that is the exponent on 10.

2.1 THE MEASURES OF SCIENCE If you moved the decimal left, n is

positive. If you moved it right, n is negative.

Practice problems 1-3, p. 20

2.1 THE MEASURES OF SCIENCE Factor-Label method (unit conversion) Remember that you can multiply 1 times

anything without changing its value. A conversion factor is a multiplier equal to 1. Because 1kg = 1000g, the following factors

can be established…1 = 1kg/1000g = 1000g/1kg

Choose the conversion factor that cancels units in the way that is helpful to your problem.

2.1 THE MEASURES OF SCIENCE Units cancel just like in algebraic

equations. Sometimes, you may have to use more

than one conversion factor if there is no direct conversion between units.

Practice problems 4 & 5, p. 21

2.1 THE MEASURES OF SCIENCE Assignment: p. 38-39, #’s 1-6, 30, 31 Key Terms for section 2.1 from p. 37

into your notebook.

2.1 THE MEASURES OF SCIENCE Addition or Subtraction of numbers in

scientific notation… Make sure numbers have the same exponent

(convert one or the other, if necessary). Add or subtract the values of M and keep the

same n. Be sure that your final answer is in proper

scientific notation.

Practice Problems 6-8, p. 22

2.1 THE MEASURES OF SCIENCE Multiplication or Division of numbers in

scientific notation… To multiply… multiply the M’s and add the

n’s To divide… divide the M’s and subtract

the n’s Be sure that your final answer is in proper

scientific notation.

Practice Problems 9-14, p. 23

2.1 THE MEASURES OF SCIENCE Assignment: Physics Skills Packet 1, #’s

1-16