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Understanding Standards of Measurement

Understanding Standards of Measurement. Standards p. 14 . Exact quantity that people agree to use to compare measurements Ex. 1 foot = 12 in. 60 min = 1 hr. 60 sec = 1 min. 3 feet = 1 yard. Universal Measurement Systems.

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Understanding Standards of Measurement

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  1. Understanding Standards of Measurement

  2. Standards p. 14 Exact quantity that people agree to use to compare measurements • Ex. • 1 foot = 12 in. • 60 min = 1 hr. • 60 sec = 1 min. • 3 feet = 1 yard.

  3. Universal Measurement Systems • Metric System is used everywhere in the world. Especially among the science community. • US wanted to be different from Europe and as a result adopted a different set of standards when they became an independent country. • Many people believe that one day we will switch back to the Metric System. (Most car speedometers have both Metric and US.

  4. SI Prefixes p.15 SI Base Units • Length = meter (m) • Mass = kilograms (kg) • Time = seconds (s) • Electric Current = Ampere (A) • Temperature = Kelvin (K) • Amount of Substance = mole (mol) • Intensity of light = candela (cd) Common SI prefixes • Kilo- (k) = 1000 (base units) • Deci- (d) = 0.1 (base units) • Centi- (d) = 0.01 (base units) • Milli- (m) = 0.001 (base units) • Micro- (μ) = 0.000001 • Nano- (n) = 0.000000001

  5. How to remember? Kids Hate Deans Because Deans Call Mom • Kilo - • Hecto – • Deka – • Base Unit • deci- • centi – • milli-

  6. Length US – only us • We use metric Metric – the rest of the world

  7. Let’s Measure! Rule: When Measuring you do what you know for sure + 1 estimated digit Our Chance for Error! What is the length of the bolt? 10.69 ± .01 cm Each big number represents a cm Our estimated digit

  8. Let’s Practice! Our estimated digit What is the width of the nut? 1.29 ± .01 cm This would have 3 significant digits

  9. What are significant digits (figures)? • Often called Significant Figures • a number are those digits that carry meaning contributing to its precision

  10. Let’s Practice! What is the length of the of pencil? 8.65 ± .01 cm This would have 3 significant digits You can only get as precise as the instrument you are using.

  11. Which devise is more Precise? Why? 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

  12. Volume • Use a graduated cylinder • Units of measurements is liters(L) What is the volume of the liquid? This is where you measure 30.1 mL

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