Thursday, August 18, 2016 Welcome to Investigative Science with Mr. Fireng

Transcription

1 Thursday, August 8, 06 Welcome to Investigative Science with Mr. Fireng.Get out your stampsheet.get out your homework.write tomorrow s homework in agenda.start WORKING QUIETLY

2 Learning goal: Properly apply all steps in the scientific method when problem solving. Learning goal: Properly apply all steps in the scientific method when problem solving. Learning scale: Name the steps Name the steps Can design and Design and carry and follow conduct an out an investigation directions in an investigation leading to a valid Student s self-evaluation: investigation Complete at home leading or at to the a end of class, and rational use the system of understanding conclusion conclusion Student s self-evaluation: Complete at home or at the end of class, use the --- Learning scale (two to three sentences). Design, complete, valid conclusion Design & complete Know steps, follow directions Know the steps

3 in of

4 The Metric System The metric system is a measurement system our decimal (base 0) number system. Other countries and all scientists and engineers use the metric system for measurement. in of. 0 0

5 SI Units SI unit for length is the Meter (m) Length is the distance between two points in of. 0 0

6 SI Units SI unit for mass is the Gram (g) Mass is how much matter is in an object in of. 0 0

7 Mass and Weight are not the same!! MASS vs. WEIGHT Always remains constant Depends on gravity in Does not depend on gravity weight=mass x gravity weight of an object changes if the gravity changes of. 0 0

8 SI Units SI unit for volume is the Liter (L) Volume is how much space a liquid takes up in of. 0 0

9 Metric prefixes Kilo means thousand (000) Hecto means hundred (00) Deca means ten (0) Deci means one-tenth (/0) in of Centi means one-hundredth (/00). 0 0 Milli means one-thousandth (/000)

10 Pneumonic device to memorize prefixes King Henry Died Unexpectedly Drinking Chocolate Milk in of Memorize. 0 0 this!

11 Do: Let s add the gram line: k h d u d c m km hm dam m dm cm mm kl hl dal l dl cl ml kg hg dag g dg cg mg. 0 0 in of

12 How to use this device:. Look at the problem. Look at the unit that has a number. On the device put your pencil on unit on problem.. Move to new unit, counting jumps and noticing the direction of the jump.. Move decimal in original number the same # of spaces and in the same direction in of

13 Example #:. Move to new unit, counting jumps and noticing the direction of the jump! k h d u d c m kl hl dal L dl cl ml in of. 0 0 Three jumps to the left!

14 Example #: 7.5 L = kl 7.5 L =.0075 kl. 0 0 in of

15 in of

16 Zero Balance. Move all three sliders so that they read zero. Make sure that there is nothing on the pan and that it is clean. Check to see if the balance reads zero. in of

17 Balance Setup. Your balance isn t reading zero so you need to turn the thumbscrew to adjust the balance until it reads zero in of

18 Balance Setup Your balance is ready to measure. Place object to be weighed on the pan. Make sure that no part of the object is supported by the table. in of

19 Moving Sliders. Start with the largest slider. Move the slider until balance tips, move the slider back to the previous position, move to the next slider.. Continue until the final slider until the balance reads zero. in of

20 5. Read each of the sliders and add their weights together. The sliders indicate the mass is: 7 g in of

21 Reading the Graduated. Read at eye level. Read to the bottom of the MENISCUS Cylinder Do:..Draw this: in of

22 What if you need to Convert Between Different Units that are not metric? How many seconds are in a day? How many inches are in a centimeter? If you are going 50 miles per hour, how many meters per second are you traveling? To answer these questions you need to change (convert) from one unit to another. in of

23 Page 8 What is dimensional analysis? What is a conversion factor? Steps for dimensional analysis.... Example: Summary: Metric System Write all Cues!! Design, complete, valid conclusion Design & complete Know steps, follow directions Know the steps

24 Dimensional Analysis Whenever you have to convert a physical measurement from one dimensional unit to another, dimensional analysis is the method used. Dimensional analysis is a method to convert one different type of unit to another in of

25 Dimensional Analysis How does dimensional analysis work? It will involve some easy math (Multiplication & Division) In order to perform any conversion, you need a conversion factor. any two terms that describe the same or equivalent amounts of what we are interested in. For example, we know that: inch =.5 centimeters dozen = in of

26 Conversion Factors So, conversion factors are nothing more than equalities or ratios that equal to each other. In mathtalk they are equal to one. In mathematics, the expression to the left of the equal sign is equal to the expression to the right. They are equal expressions. For Example inches = foot Written as an equality or ratio it looks like in of = or =

27 Conversion Factors in of

28 Conversion Factors Conversion Factors look a lot like fractions, but they are not! They are ratios or Either one is correct But! The critical thing to note is that the units behave like numbers do when you multiply fractions. That is, the inches (or foot) on top and the inches (or foot) on the bottom can cancel out. Just like in algebra, or in of

29 Steps for dimensional analysis Example Problem # How many feet are in 60 inches? Solve using dimensional analysis. in of

30 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Read the problem and find out what unit you are in, and what unit you want to get to, then write what you have below it. Put a below it ad a X. What units you have----- inches feet What units you want in of 60 inches x

31 Steps for dimensional analysis (Have) Example Problem #How many feet are in 60 inches? Step : Read the problem and find out what unit you are in, and what unit you want to get to, then write what you have below it. Put a below it ad a X. What units you have----- inches feet What units you want in of 60 inches x

32 Steps for dimensional analysis (Want) Example Problem #How many feet are in 60 inches? Step : Read the problem and find out what unit you are in, and what unit you want to get to, then write what you have below it. Put a below it ad a X. What units you have----- inches feet What units you want in of 60 inches x

33 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Read the problem and find out what unit you are in, and what unit you want to get to, then write what you have below it. Put a below it ad a X. What units you have----- inches feet What units you want in of 60 inches x

34 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Read the problem and find out what unit you are in, and what unit you want to get to, then write what you have below it. Put a below it ad a X. What units you have----- inches feet What units you want in of 60 inches x

35 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Find the conversion factor, put the unit you have on the bottom. Inches feet or Use this one.. in of

36 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Set up the problem, unit you have X conversion factor = units you want. 60 inches x = feet in of

37 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Set up the problem, unit you have X conversion factor = units you want. 60 inches x = feet in of What units you have x What units you want What units you have = What units you want

38 Steps for dimensional analysis Example Problem #How many feet are in 60 inches? Step : Cancel the units and solve the problem! 60 inches Now you have the unit you want.. x = 5 feet (Mathematically all you do is: 60 x = 5) in of

39 Steps for dimensional analysis Example Problem # How many feet are in 60 inches? Step : 60 inches inches feet in of

40 Steps for dimensional analysis Example Problem # How many feet are in 60 inches? Step : 60 inches inches feet Step : Use this one! in of

41 Steps for dimensional analysis Example Problem # How many feet are in 60 inches? Step : Step : 60 inches inches feet Step : x = feet Use this one! in of

42 Steps for dimensional analysis Example Problem # How many feet are in 60 inches? Step : Step : Step : 60 inches 60 inches inches feet x Step : x = feet = 5 feet (60 x = 5) Use this one! in of

43 Example Problem # (cont) The previous problem can also be written to look like this: in 60 inches foot = 5 feet inches This format is more visually integrated, more bridge like, and is more appropriate for working with factors. In this format, the horizontal bar means divide, and the vertical bars mean multiply. of

44 Dimensional Analysis in of

45 Dimensional Analysis The hardest part about dimensional analysis is knowing which conversion factors to use. Some are obvious, like inches = foot, while others are not. Like how many feet are in a mile. in of

46 Example Problem # You need to put gas in the car. Let's assume that gasoline costs $.5 per gallon and you've got a twenty dollar bill. How many gallons of gas can you get with that twenty? Try it! $ 0.00 gallon = 5.97 gallons $.5 in of (Mathematically all you do is: 0 x.5 = 5.97)

47 Example Problem # What if you had wanted to know not how many gallons you could get, but how many miles you could drive assuming your car gets miles a gallon? Let's try building from the previous problem. You know you have 5.97 gallons in the tank. Try it! in of 5.97 gallons miles =.8 miles gallon (Mathematically all you do is: 5.97 x =.8)

48 Example Problem # There's another way to do the previous two problems. Instead of chopping it up into separate pieces, build it as one problem. Not all problems lend themselves to working them this way but many of them do. It's a nice, elegant way to minimize the number of calculations you have to do. Let's reintroduce the problem. in of

49 Example Problem # (cont) You have a twenty dollar bill and you need to get gas for your car. If gas is $.5 a gallon and your car gets miles per gallon, how many miles will you be able to drive your car on twenty dollars? Try it! $ 0.00 gallon miles =.8 miles $.5 gallon in of (Mathematically all you do is: 0 x.5 x =.8 )

50 Example Problem # Try this expanded version of the previous problem. You have a twenty dollar bill and you need to get gas for your car. Gas currently costs $.5 a gallon and your car averages miles a gallon. If you drive, on average, 7. miles a day, how many weeks will you be able to drive on a twenty dollar fill-up? in of

51 Example Problem # (cont) $ 0.00 gallon miles day week $.5 gallon 7. miles 7 days =.88 weeks in of (Mathematically : 0 x.5 x x 7. x 7 =.88 )

52 Dimensional Analysis So you can have a simple step problem or a more complex multiple step problem. Either way, the set-up of the problem never changes. You can even do problems where you don t even understand what the units are or what they mean. Try the next problem. in of

53 Example Problem #5 If Peter Piper picked 8 pecks of pickled peppers, how many barrels is this? Peter Piper picked a peck of pickled peppers... Or so the rhyme goes. (What in the world is a peck?) You need help for this one. As long as you have information (conversion factors) you can solve this ridiculous problem. in of

54 05 dry quarts or barrel. barrel 05 dry quarts Example Problem #5 (cont) Use this info: A peck is 8 dry quarts: a bushel is pecks or dry quarts; a barrel is 05 dry quarts. WHAT?! Rewrite them as conversion factors if the info is not given to you that way. 8 dry quarts or peck. peck 8 dry quarts pecks or bushel bushel pecks dry quarts or bushel. bushel dry quarts in of

55 Example Problem #5 Pick the conversion factors that will help get to the answer. 8 pecks barrel. Hint: Look for units that will cancel each other. 8 pecks 8 dry quarts barrel peck 05 dry quarts = 6. barrels in of (Mathematically : 8 x 8 x 05 = 6. )

56 Review Dimensional Analysis (DA) is a method used to convert from one unit system to another. In other words a math problem. Dimensional Analysis uses Conversion factors. Two terms that describe the same or equivalent amounts of what we are interested in. All DA problems are set the same way. Which makes it nice because you can do problems where you don t even understand what the units are or what they mean.