BELLWORK 8/15/17 What is the SI unit for length? Mass? Time?

Measurements in Science Ch1.2 Scientists use various measurements in Science to record and express their results. The first system of measurement that we will explore is the SI System.

1. SI System When scientists do research, they must communicate their results with each other. In 1960, an international committee agreed upon a system of standards that would be used, and they called it, the Systeme International d’Units (SI). In SI, there are only seven base units, with each unit describing a single dimension.

There are 3 SI Units that we will use this year Meter, Kilogram, and seconds, Can you name the other 4 SI Units?

ANSWERS Ampere (A)– Electric current Kelvin ( K) – Temperature Mole ( mol) – the amount of really small particles Candela (cd) – luminous intensity

SI Measurements (cont) These units are defined by the standards described in Table 2 and are reproduced so that every meterstick, kilogram mass, and clock in the world is calibrated to give consistent results.

SI Uses Derived Units Derived units are formed by combining the seven base units with multiplication or division. Ex: speed is measured in m/s Ex: Force is measured in Newtons which is kg • m/s2

Prefixes Scientists use prefixes to express really large or really small variations of the base units. The base unit is combined with prefixes that symbolize certain powers of 10. Ex: The length of a housefly is 5 x 10-3m, or 5 mm. The prefix milli means 10-3 power of a meter.

2. Scientific Notation The 2nd System of Measurements used by scientists is Scientific Notation.

The mass of one gold atom is .000 000 000 000 000 000 000 327 grams. Scientific Notation is used to express very large and very small numbers so that problem solving will be easier. Examples: The mass of one gold atom is .000 000 000 000 000 000 000 327 grams. One gram of hydrogen contains 602 000 000 000 000 000 000 000 hydrogen atoms. Scientists can work with very large and very small numbers more easily if the numbers are written in scientific notation.

How to Use Scientific Notation In scientific notation, a number is written as the product of two numbers….. …..A coefficient and 10 raised to a power.

For example: 4.5 x 103 The coefficient is _______. 4.5 The number 4,500 is written in scientific notation as ________________. 4.5 x 103 The coefficient is _______. 4.5 The coefficient must be a number greater than or equal to 1 and smaller than 10. The power of 10 or exponent in this example is _____. 3 The exponent indicates how many times the coefficient must be multiplied by 10 to equal the original number of 4,500.

Rules to Remember! If a number is greater than 1, the exponent will be __________ and is equal to the number of places the decimal must be moved to the _____ to write the number in scientific notation. positive left

Rules to Remember! right If a number is less than 1, the exponent will be ___________ and is equal to the number of places the decimal must be moved to the _______ to write the number in scientific notation. negative right

A number will have an exponent of zero if: ….the number is between 1 and 9.

To write a number in scientific notation: 1. Move the decimal as many places as needed to create a coefficient between 1 and 10. 2. Count how many places the decimal had to be moved. 3. If the decimal had to be moved to the right, the exponent is negative. 4. If the decimal had to be moved to the left, the exponent is positive. To emphasize again: The exponent counts how many places you move the decimal to the left or right.

Practice Problems PROBLEMS: ANSWERS 1.2 x 10-4 1 x 103 0.00012 Express the following in scientific notation. PROBLEMS: 1.2 x 10-4 1 x 103 1 x 10-2 1.2 x 101 9.87 x 10-1 5.96 x 102 7.0 x 10-7 1.0 x 106 1.26 x 10-3 9.88 x 1011 8 x 100 ANSWERS 0.00012 1000 0.01 12 0.987 596 0.000 000 7 1,000,000 0.001257 987,653,000,000 8

EXPRESS THE FOLLOWING AS WHOLE NUMBERS OR AS DECIMALS PROBLEMS ANSWERS 4.9 X 102 3.75 X 10-2 5.95 X 10-4 9.46 X 103 3.87 X 101 7.10 X 100 8.2 X 10-5 490 .0375 .000595 9460 38.7 7.10 .000082

CLASSWORK COMPLETE SCIENTIFIC NOTATION WKSHT #1

Multiplying and Dividing with Scientific Notation You need to learn how to enter numbers in scientific notation into your calculators. We will use the EXP key to enter numbers . Ex: (3.45 x 10-5 ) x 2.3 x 107 =