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The International System of Units

The International System of Units. Based on the #10 Makes conversions easier Old name = metric system. Units and Quantities. Length – the distance between 2 points or objects Base unit = meter Volume – the space occupied by any sample of matter

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The International System of Units

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  1. The International System of Units www.assignmentpoint.com

  2. Based on the #10 • Makes conversions easier • Old name = metric system www.assignmentpoint.com

  3. Units and Quantities • Length – the distance between 2 points or objects Base unit = meter • Volume – the space occupied by any sample of matter V = length x width x height Base unit = liter Based on a 10cm cube (10cm x 10cm x 10cm = 1000cm3) 1 liter = 1000cm3 www.assignmentpoint.com

  4. Mass – the amount of matter contained in an object Base unit = gram Different than weight… Weight - a force that measures the pull of gravity www.assignmentpoint.com

  5. www.assignmentpoint.com

  6. Temperature – a measure of the energy of motion How fast are the molecules moving? When 2 objects are at different temperatures heat is always transferred from the warmer → the colder object www.assignmentpoint.com

  7. Temperature Scales • Celsius scale – Freezing point of H2O = 0oC Boiling point of H2O = 100oC • Kelvin scale – Freezing point of H2O = 273.15K Boiling point of H2O = 373.15K K = C + 273 C = K - 273 www.assignmentpoint.com

  8. Temperature Scale Conversions www.assignmentpoint.com

  9. Conversion FactorsandUnit Cancellation www.assignmentpoint.com

  10. A physical quantity must include: Number + Unit www.assignmentpoint.com

  11. 1 foot = 12 inches www.assignmentpoint.com

  12. 1 foot = 12 inches 1 foot =1 12 inches www.assignmentpoint.com

  13. 1 foot = 12 inches 1 foot =1 12 inches 12 inches =1 1 foot www.assignmentpoint.com

  14. 1 foot 12 inches 12 inches 1 foot “Conversion factors” www.assignmentpoint.com

  15. 1 foot 12 inches 12 inches 1 foot “Conversion factors” How many inches are in 3 feet? 12 inches ( ) ( ) =36 inches 3 feet 1 foot www.assignmentpoint.com

  16. 100 cm ______ 100 cm 1 m ______ 1 m 1 m 100 cm ______ 132 cm ( ) equality: 1 m = 100 cm conversion factors: How many cm are in 1.32 meters? or X cm = 1.32 m = We use the idea of unit cancellation to decide upon which one of the two conversion factors we choose. www.assignmentpoint.com

  17. 0.0872 m 100 cm ______ 1 m ______ 1 m 100 cm ______ ( ) 1 m 100 cm equality: 1 m = 100 cm conversion factors: How many meters is 8.72 cm? or X m = 8.72 cm = Again, the units must cancel. www.assignmentpoint.com

  18. 1 ft ______ 1 ft 12 in 12 in ( ) 12 in ______ ____ 1 ft 3.28 ft equality: 1 ft = 12 in How many feet is 39.37 inches? conversion factors: or X ft = 39.37 in = Again, the units must cancel. www.assignmentpoint.com

  19. 1 km 1,000 m ( ) ______ ( ) ____ 1 m 10 dm 1.5 km How many kilometers is 15,000 decimeters? X km = 15,000 dm = www.assignmentpoint.com

  20. ( ) _____ 60 min 1 h 378,432 s ( ) ( ) ____ 60 s 3.78 x 105 s ____ 24 h 1 min 1 d How many seconds is 4.38 days? X s = 4.38 d = If we are accounting for significant figures, we would change this to… www.assignmentpoint.com

  21. Why do some objects float in water while others sink? • Need to know the ratio of the mass of an object to it’s volume • Pure H2O at 4oC = 1.000g/cm3 • If an object has a lower ratio it will float • If an object has a greater ratio it will sink www.assignmentpoint.com

  22. Density • The ratio of an object’s mass to it’s volume Density = mass volume Example: A 10.0cm3 piece of lead has a mass of 114g. What is the density of lead? 114g = 10.0cm3 11.4g/cm3 www.assignmentpoint.com

  23. Recall… What type of property is density? Does the density of a material change in relation to the sample size? NO… density is an Intensive property it depends only on the composition of the material www.assignmentpoint.com

  24. What might affect a substance’s density? • Temperature • The volume of most substances ↑ with an ↑ in temperature • the mass remains the same If the volume increases… what affect does it have on a substance’s density? The density decreases *Exception – Water’s volume ↑ with a ↓ in temperature Its density decreases & ice floats H2O www.assignmentpoint.com

  25. M V D Calculating Density What is the volume of a pure silver coin that has a mass of 14g, and a density of 10.5g/cm3? D = 10.5g/cm3 M = 14g V = ? Rearrange the density formula to solve for V www.assignmentpoint.com

  26. g g V = M D V = 14g = 14 x 1 cm3= 10.5g/cm3 10.5 1.3cm3 www.assignmentpoint.com

  27. M V D cm3 cm3 What is the mass of mercury that has a density of 13.5g/cm3 and a volume of 0.324cm3? Once again, rearrange the density formula… and solve for M. M = D x V = 4.62g M = 13.5g x 0.342 www.assignmentpoint.com

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