Metric System

“Inch by inch, life’s a cinch. Yard by yard, life is hard.” author unknown

Measurement Systems: English – only used in the United States Metric – used all over the world (International System of Units – S.I.)

Most Common Base Units Meter – measures length(distance between 2 points) Gram – measures mass (amount of matter in an object) kg Liter – measures liquid volume(amount of space an object takes up) Kelvin, Celsius – measures temperature

Prefixes Added to Base Units: Kilo (1000) – k Hecto (100)– h Deka (10)- dk Deci(1/10)– d Centi(1/100)– c Milli(1/1000)–m

Conversions: Base K h dk Liter d c m Gram Meter King Henry Died By Drinking Chocolate Milk

Example: K h dk Liter d c m Gram Meter

Instruments: Length – metric ruler, meter stick Mass – triple beam balance Volume (liquid) – graduated cylinder Volume (regular solid) –metric ruler Volume (irregular solid) – graduated cylinder Temperature – thermometer

Formulas: Volume of a solid - length x width x height unit = cm3 Temperature: 0 F = (1.8 x 0 C) + 32 0 F = (9/5 x 0 C) + 32 0C = .56 ( 0 F - 32) 0C = 5/9 ( 0 F - 32) ? 0 C = K – 273 ? K = 0 C + 273

Making Measurements: “Only those who have the patience to do simple things perfectly will acquire the skill to do difficult things easily.” Johann von Schiller

Measurements in Science: In Science, we want measurements to be both accurate and precise. What is the difference between accurate and precise?

Accurate (accuracy) capable of providing a correct reading or measurement. correctly reflects the size of the thing being measured. refers to how closely a measured value agrees with the correct value.

Precise(precision) Repeatable Reliable getting the same measurement each time. refers to how closely individual measurements agree with each other.

Examples: The Forecast is between 40 and 60 degrees today. The actual reading turns out to be 53. Thus, the forecast was accurate, but not very precise.

Examples: The forecast is 52.47 degrees at 4 PM. It turns out to be 61 degrees. This forecast was very precise, but completely inaccurate.

Neither accurate nor precise random

Precise, but not accurate

Accurate but not precise Average is center of Bull’s eye.

Accurate and Precise

Emma: 5.0 cm Group 1: Group2: Group3: 3.111 5.0 5.0012 3.111 4.9 5.0150 3.111 5.0 5.0001 Which group is accurate? Which group is precise? Which group is accurate and precise

Significant Figures (digits): Tell us how precise a measurement is. The significant figures in a measurement include all the digits that can be known precisely plus a last digit that is an estimate.

Rules for Significant Figures: Any non zero digits are significant. example – 4.5 (2 SF) Any zeros between numbers are significant. example – 10.5 (3 SF) Zeros to the left of the 1st non-zero digit are NOT significant. example – 0.0205 (3 SF)

More Rules: 4. Final zeros after the decimal are significant. example – 1.00 (3 SF) 5. Zeros to the right of the last non zero digit without a decimal point are not significant. example – 123,000 (3SF)

If you like the Atlantic Pacific rule – check out the ppt entitled Significant Figures