Click to add text Significant Figures Physical Science

What is a significant figure? There are 2 kinds of numbers: –Exact : Known for certain. Ex: 12 donuts in a dozen Ex: Samantha has 10 fingers Ex: 60 seconds in a minute

What is a significant figure? There are 2 kinds of numbers: Measured : Acquired by measuring things. Have some degree of uncertainty. Ex: The pencil is 7.48 inches Ex: Tommy weighs pounds Ex: The student's hand was raised for 2 minutes and 16 seconds.

When to use Significant figures –DONT WORRY ABOUT SIGNIFICANT FIGURES FOR EXACT NUMBERS, BUT YOU ABSOLUTELY NEED THEM FOR MEASURED ONES!

When to use Significant figures –If you measured how tall your paper is, you might read it as 29.7cm or maybe 29.70cm....In math class, 29.7, 29.70, and is the same thing.

But, to a scientist 21.7cm and 21.70cm is NOT the same To a scientist, the number of significant figures represents how PRECISE the measurement is. More decimals → More precise measurement. This reflects the precision of tools used to take the measurement.

Golden rule for scientific measurement Record all digits that you can be certain of. Then, record ONE additional digit that you have estimated. The more precise the instrument, the more digits you may record. All recorded digits are significant.

How do I know how many Sig Figs? #1. All non-zero digits are ALWAYS significant. I mean it. ALWAYS. #2. Zeroes that are “captured” between significant digits are also significant. #3. Trailing zeroes are only significant IF THERE IS A DECIMAL in the number.

How many sig figs? ,000,000

What about adding/subtracting? Rule: When adding or subtracting measured numbers, the answer can have no more places after the decimal than the LEAST of the measured numbers.

Multiplication and Division Rule: When multiplying or dividing, the result can have no more significant figures than the least precise measurement.

Scientific notation Special notation used for very large or very small numbers. Utilizes powers of 10. Instead of 1,000,000,000 – write 1 x THE NUMBER OF SIGNIFICANT FIGURES MUST STAY THE SAME!!

Metric prefixes The metric system is based around how many ORDERS OF MAGNITUDE a unit is away from a base unit. Memorize these: Mass → GRAM (g) Distance → METER (m) Time → SECOND (s) Volume → LITER (L)

Metric prefixes You are expected to be able to recognize 6 prefixes commonly used in the metric system. - Base unit = meters (m) x10 1 = decameters (dam) || x10 -1 = decimeters (dm) x10 2 = hectometers (hm) || x10 -2 = centimeters (cm) x10 3 = kilometers (km) || x10 -3 = millimeters (mm)

Metric prefixes To convert from one unit to another, count how many orders of magnitude they are apart, then move the decimal over that many places. Ex: Convert decameters to kilometers. dm → 10 1, km → Deca is 2 orders lower than Kilo. Move two decimal places to the left dm (4 S.F.) = 3.000km (4 S.F.) SIGNIFICANT FIGURE STAY THE SAME!

Click to add text The End Have Fun Measuring and Happy Calculating!