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Homework pg. 15

Homework pg. 15. Perform the following calculations: 1.5 x 10 3 m x 1.0 x 10 5 4.5 x 10 3 / 0.9. Units and Standards. Standard =. an exact quantity that people agree to use for comparison. International System of Units SI. SI. is the standard system of measurement used worldwide.

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Homework pg. 15

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  1. Homework pg. 15 • Perform the following calculations: • 1.5 x 103m x 1.0 x 105 • 4.5 x 103 / 0.9

  2. Units and Standards • Standard = an exact quantity that people agree to use for comparison.

  3. International System of Units SI • SI is the standard system of measurement used worldwide. All SI standards are universally accepted and understood by scientists.

  4. Each type of Measurement has a base unit (length, time, temp., volume, density). • SI = easy, because it is based on the power of ten

  5. Limits of Measurements • Significant Figures=all digits measured + the last digit estimated. • Precision= calculated by the least precise measurement used. (10.1 or 10.095) • Accuracy= the closeness of a measurement to the actual value. (2 watches, 1 right time & the other off by 2 mins.)

  6. Length • The SI base unit of length is the METER (m)

  7. Choosing a unit • The size of the unit used to measure with depends on the size of the item measured. • Ex. cm. to measure a pencil km. for distance between cities

  8. Conversion Rules • All measurements have two parts: a number and a unit • Convert larger to smaller, multiply. • Convert smaller to larger, divide.

  9. Conversion Rules • Ex: Convert 532 cm to meters, divide because you’re converting from smaller (cm) to larger (m). Because 100 cm = 1 m so divide 532 by 100.

  10. Using Math : Converting Meters to Centimeters: • How many centimeters are in 1.98 meters? • Problem Solving Steps: • 1. What is known?: • 1 m = 100 cm (You are converting from larger to smaller units) • 2. When converting from larger to smaller units, multiply.

  11. Using Math : Converting Meters to Centimeters: • How many centimeters are in 1.98 meters? • Problem Solving Steps: • 1. What is known?: • 1 m = 100 cm (You are converting from larger to smaller units) • 2. When converting from larger to smaller units, multiply.

  12. Volume • the amount of space occupied by an object. • Measure length, width, height and multiply • L x W x H • Volume might be expressed in cubic centimeters • cm3 or in cubic meters m3 for example.

  13. Measuring Volume • Volume units are obtained by combining other SI units of length. • Derived Units = Units obtained by combining SI units.

  14. Measuring Volume • The most common units for expressing liquid volumes are liters and milliliters. Liter = occupies the same volume as a cubic decimeter (dm3). That is, a liter is the same volume as a cube that is 1 dm (10cm) on each side. (see figure 2-6 on page 42) • The liter is not an SI unit, but it is used frequently with that system.

  15. Mass • Mass = • -a measurement of the matter in an object. • -Kilogram (kg) = The SI unit of mass.

  16. Density • Density= the mass per unit volume of a material. • -Like volume, density is a derived unit. • -You can find the density of an object by • dividing its mass by its volume. • Both mass and volume are used • to express density.

  17. Time and Temperature the interval between two events. • Time = • Second = the SI unit for time.

  18. Temperature • For most scientific work, temperature is measured on the Celsius (C) scale. • The freezing point of water is zero degrees (0°C), and the boiling point of water is one hundred degrees (100°C).

  19. Kelvin (K) • The SI unit of temperature. • Zero (0 K) on the Kelvin scale is the coldest possible temperature, also known as absolute zero. That is -273°C, which is 273 degrees below the freezing point of water.

  20. Kelvin Temperature • Kelvin temperature can be found by adding 273 to the Celsius reading. • On the Kelvin scale, water freezes at 273 K and boils at 373 K. • Degree symbols are not used in the Kelvin scale.

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