1 / 19

Chapter 2-2 Units of Measurement

Chapter 2-2 Units of Measurement. Modification of Mrs. Rugh’s presentation 9/22/14. Measurements. Measurements are information that represent quantities. Measurement is different from Quantity. Measurements. A quantity is something that has size, magnitude, or amount.

gloriahammond
Download Presentation

Chapter 2-2 Units of Measurement

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 2-2Units of Measurement Modification of Mrs. Rugh’s presentation 9/22/14

  2. Measurements • Measurements are information that represent quantities. • Measurement is different from Quantity

  3. Measurements • A quantity is something that has size, magnitude, or amount. • Example: 1 teaspoon Unit of measurement Measurement Quantity is volume

  4. Measurement Standards Le Systeme International d’Unites (SI) • Adopted in 1960 by the General Conference on Weights and Measures. • Now used and agreed upon by scientists around the world. • This is basically what we call the “metric” system

  5. SI system • Has 7 “base units” • Most other units are derived from combinations of 2 or more “base units” • Not all units in this book are SI units

  6. Measurement Standards • SI Units are defined in terms of standards of measurements. • In 1795 the meter was defined as one ten-millionth of the distance from the Earth's equator to the North Pole (at sea level) • Before 1927 the official meter was defined by the length of a platinum-iridium bar kept in France. • Since 1983, the meter has been defined as "the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second."[2]

  7. Measurement Standards • Kilogram is the base unit of mass and is defined as being equal to the mass of the International Prototype of the Kilogram (IPK). • It is the only SI unit that is still defined by an artifact instead of a physical property. • However, there is discussion to define the kilogram in terms of a fundamental constant of nature.

  8. Measurement Standards • The second is the base unit of time • Since 1967, the second has been defined to be: • the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.[

  9. SI Base Units Quantity Unit Unit Quantity symbol name abbreviation Length lmeter m Mass m gram g Time t second s Temperature Tkelvin K Amount of nmole mol substance You have a handout with this information on it…

  10. Mass ≠ Weight • Mass is a measure of the amount of matter, weight depends on the local gravitational field. • We usually measure mass with a balance, weight is usually measured with a spring scale. • We will talk about MASS only in this class (leave weight for physics…

  11. Prefixes –what do they MEAN • The handout has the important prefixes you need to know on it. • You should know the prefixes on the handout because you will use them…over and over…and over again.

  12. Prefixes –what do they MEAN • Come up with one example of what you might measure with each of these units in meters.

  13. Which unit (with appropriate prefix) would you use to measure this stuff? • Diameter of an atom • Weight of an elephant • Area of the Tacoma Dome • Temperature of the summit of Mt. Rainier • Temperature in outer space

  14. Derived SI Units • Derive v. • Mathematics: Obtain (a function or equation) from another by a sequence of logical steps, for example by differentiation: the volume fraction of the soil can then be derived as a function of L Oxforddictionary.com

  15. Derived SI Units • derived units…units that are created by combining 2 or more SI Base Units (usually through multiplying or dividing base units). • For example: • Length (m) x Length (m) = Area (m2) • Mass (kg)/Volume (m3) = Density (kg/m3)

  16. Example: Volume • The amount of space occupied by an object. • Solids: m x m x m = m3 • Liquids and gases: 1 Liter = 1 dm3 = 1000 cm3 So 1 mL = 1 cm3

  17. Density • The ratio of mass to volume, or mass divided by volume • D = mass/volume or D = m/v • Often (though not always) expressed in units of g/cm3.

  18. Quick Check

  19. Now Do the Practice Problems Due tomorrow if you don’t finish in class…

More Related