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To learn how dimensional analysis can be used to solve problems To learn the three temperature scales

Objectives. To learn how dimensional analysis can be used to solve problems To learn the three temperature scales To learn to convert from one temperature scale to another To practice using problem solving techniques To define density and its units . A. Tools for Problem Solving .

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To learn how dimensional analysis can be used to solve problems To learn the three temperature scales

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  1. Objectives • To learn how dimensional analysis can be used to solve problems • To learn the three temperature scales • To learn to convert from one temperature scale to another • To practice using problem solving techniques • To define density and its units

  2. A. Tools for Problem Solving • I am driving in Canada. I have a journey of 120 km and I need to estimate how many liters of gas to buy. I know my car fuel mileage is 24 miles per gallon. (1 mile is 1.6 km, 1 gallon is 3.79 liters) • Be systematic • Ask yourself these questions • What do we know to start with? • Where do we want to go? • How do we get there? • Does it make sense?

  3. A. Tools for Problem Solving • Converting Units of Measurement • We can convert from one system of units to another by a method called dimensional analysis using conversion factors. • Unit1 conversion factor = Unit2

  4. A. Tools for Problem Solving • Converting Units of Measurement • Conversion factors are built from an equivalence statement which shows the relationship between the units in different systems. 1 inch = 2.54cm or 1 cm = 0.394 inches • Conversion factors are ratios of the two parts of the equivalence statement that relate the two units. 1 inch or2.54cmor0.394 inchesor 1 cm . 2.54cm 1 inch 1 cm 0.394 inches

  5. A. Tools for Problem Solving • Converting Units of Measure 2.85 cm = ? in.2.85 cm conversion factor = ? in. Equivalence statement 2.54 cm = 1 in.Possible conversion factors Does this answer make sense?

  6. A. Tools for Problem Solving • Tools for Converting from One Unit to Another Step 1 Find an equivalence statement that relates the 2 units.Step 2 Choose the conversion factor by looking at the direction of the required change (cancel the unwanted units).Step 3 Multiply the original quantity by the conversion factor. Step 4 Make sure you have the correct number of significant figures. Go back and solve the Driving Problem in Canada

  7. 32 Degrees?

  8. ..or 32 Degrees?

  9. . . . . . . . . . . . . . . . . . . 32 Degrees? . .

  10. B. Temperature Conversions • There are three commonly used temperature scales, Fahrenheit, Celsius and Kelvin.

  11. B. Temperature Conversions • Note that • The temperature unit is the same size. • The zero points are different. • To convert from Celsius to Kelvin we need to adjust for the difference in zero points. • Converting Between the Kelvin and Celsius Scales

  12. B. Temperature Conversions 70 oC = ? K TC + 273 = TK • Converting Between the Kelvin and Celsius Scales 70 + 273 = 343 K

  13. B. Temperature Conversions • Note • Converting Between the Fahrenheit and Celsius Scales • The different size units • The different zero points • To convert between Fahrenheit and Celsius we need to make 2 adjustments. ToC = ?

  14. Convert These Temperatures 200oC to K -52oC to K 345K to oC 11K to oC 212oF to oC 32oF to oC 525oF to oC 25oC to oF -20oC to oF 200oF to K

  15. At what temperature would a Celsius and a Fahrenheit thermometer read the same? ToF=ToC

  16. C. Density • Density is the amount of matter present in a given volume of substance. Write down all the statements relating the three properties D, M and V

  17. How to Remember the Density Relationships Q. Where do you get your permit? A. At the DMV m v D

  18. Calculate the Missing Quantity: Remember the “DMV” 1 lb = 454 g

  19. C. Density H2 = 0.084 kg/m3 Is the hydrogen number correct?

  20. Density of Water One gram of water has a volume of 1 milliliter The density of water is……? D = M/V Density of water = 1 g/mL or 1g/cm3 How much does 150 mL of water weigh? What is the density of water in kg/m3? (Egg density demo)

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