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Standards of Measurement

Standards of Measurement. Metric System. The metric system is based on a base unit that corresponds to a certain kind of measurement Length = meter Volume = liter Weight (Mass) = gram Prefixes plus base units make up the metric system Example: Centi + meter = Centimeter

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Standards of Measurement

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  1. Standards of Measurement

  2. Metric System The metric system is based on a base unit that corresponds to a certain kind of measurement Length = meter Volume = liter Weight (Mass) = gram Prefixes plus base units make up the metric system Example: Centi + meter = Centimeter Kilo + liter = Kiloliter

  3. Metric System These prefixes are based on powers of 10. What does this mean? From each prefix every “step” is either: 10 times larger or 10 times smaller For example Centimeters are 10 times larger than millimeters 1 centimeter = 10 millimeters

  4. Metric System For each “step” to right, you are multiplying by 10 For example, let’s go from a base unit to centi 1 liter = 10 deciliters = 100 centiliters 2 grams = 20 decigrams = 200 centigrams ( 1 x 10 = 10) = (10 x 10 = 100) (2 x 10 = 20) = (20 x 10 = 200)

  5. Metric System An easy way to move within the metric system is by moving the decimal point one place for each “step” desired Example: change meters to centimeters 1 meter = 10 decimeters = 100 centimeters or 1.00 meter = 10.0 decimeters = 100. centimeters

  6. Metric System Now let’s try our previous example from meters to kilometers: 16093 meters = 1609.3 decameters = 160.93 hectometers = 16.093 kilometers So for every “step” from the base unit to kilo, we moved the decimal 1 place to the left (the same direction as in the diagram below)

  7. Metric System If you move to the left in the diagram, move the decimal to the left If you move to the right in the diagram, move the decimal to the right

  8. Metric System Summary Base units in the metric system are meter, liter, gram Metric system is based on powers of 10 For conversions within the metric system, each “step” is 1 decimal place to the right or left Using the diagram below, converting to the right, moves the decimal to the right and vice versa

  9. Measuring Distance (Length): • Lengthis the distance between two points. • SIbase unit for length ism • We need to use different unites sometimes: • cmfor things like a pencil • Kmfor long distances like between RAK and Dubai. • 1m = 100 cm • 1Km = 1000 m • 1cm = 10 mm • 1dm = 10 cm

  10. Measuring Volume • Volume: the amount of space occupied by an object. • You’ll learn how to measure the volume of: • Regular solids, like a cube. • Liquids. • Irregular solids, like a pencil or a crown

  11. Volume of regular solids: Ex: a cube V = l x w x h = 5 cm x 5 cm x 5 cm = 125 cm3 Where cm3 is a volume unit.

  12. Measuring Mass Mass: How much matter in an object. Units: kg, g, mg, …. 1 kg = 1000 g 1g = 1000 mg Example: how many kilograms are in 6430 mg? 6.43 kg

  13. Density: is the mass per unit volume. Density = mass volume What is the density of an object having a mass of 10g and a volume of 2 cm3 ? Density = 10g = 5 g/cm3 2 cm3 The unit of density is g/cm3

  14. Density = Mass / Volume ( D = M / V ) Density x Volume = Mass ( D x V = M ) Volume = Mass / Density ( V = M / D )

  15. Measuring Time and Temperature • Time: the interval between two events. • The unit of time is the second • Temperature: measured with a thermometer and measured in Celsius or Kelvin. • Celsius ranges from 0 (freezing) to 100 (boiling). • The Kelvin scale begins at absolute zero, or 0 K. • To convert to Kelvin you add 273 degrees to the Celsius reading. • Freezing in Kelvin is 273 K, boiling is 373 K.

  16. Scientific Numbers Scientific numbers use powers of 10 2 100 = 10 x 10 = 10 3 1000 = 10 x 10 x 10 = 10 1 -1 0.10 = 1 / 10 = 10 -2 2 0.01 = 1 / 100 = 1 / 10 = 10 2 523 = 5.23 x 100 = 5.23 x 10 -2 2 0.0523 = 5.23/100 = 5.23/10 = 5.23 x 10

  17. Significant Figures 120000 No decimal point 2 sig figs Zeros are not significant! 120000. Decimal Point All digits including zeros to the left of The decimal are significant. 6 sig figs

  18. Significant Figures 1005 All figures are Significant 4 sig figs Zeros between Non zeros are significant 123.00 All figures are Significant 5 sig figs Zero to the Right of the Decimal are significant

  19. Significant Figures 0.00523 3 sig figs Zeros to the right of The decimal with no Non zero values Before the decimal Are not significant 0.0052300 5 sig figs Zeros to the right of the decimal And to the right of non zero values Are significant

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