1. Introduction to Physics

2. The Marshmallow Challenge
Task: Teams of four must build the tallest freestanding structure with the materials provided
Materials: 20 sticks of spaghetti, one meter of tape, one meter of string, and one marshmallow
Time Limit: 20 minutes
Requirements: The freestanding structure must hold the marshmallow on top

3. Bellwork
On a sheet of paper, answer the following: What are the steps of the scientific method? Submit your answer to the front.

4. Scientific Method State the problem clearly. Gather information.
Form a Hypothesis.
Test the hypothesis.
Evaluate the data to form a conclusion.
Share the results.

5. Hypothesis a working explanation or trial answer to a problem
Something that can be tested
can be written in the form of an “If..., then..., because...” statement
is not necessarily proven correct just because data/results from one experiment supports it

6. Today’s problem: What variables affect the period of a pendulum?
How do these variables affect the period?

7. Data and Measurements
We make QUALITATIVE observations of reactions We also make QUANTITATIVE MEASUREMENTS, which involve numbers. Use SI units — based on the metric system

8. Measurement
Every measurement has a Number followed by a Unit from a measuring device
The number should also be as precise as the measurement!

9. Graphing A mathematical picture
Graphs are used to show information quickly and simply
Change one variable at a time to determine relationships
Relationships we will study include linear, quadratic, and inverse

10. Two Types of Variables
Independent
variables that are purposely changed or manipulated in an experiment
the factor that you wish to test
usually expressed after the word “if” in the hypothesis
Placed on the x-axis
Dependent
variables that may change as a result of the independent variable
the factor you measure to gather results
usually expressed after the word “then” in the hypothesis
Placed on the y-axis

11. Types of Graphs

12. Types of Graphs

13. Types of Graphs

14. Graphing Terms
Interpolation- making predictions for data points not collected that fall between those that were actually tested
Extrapolation- making predictions for data points not collected that are greater than those actually tested

15. Significant Figures
The numbers reported in a measurement are limited by the measuring tool
Significant figures in a measurement include the known digits plus one estimated digit

16. Bellwork
Graph mass versus volume using the data on the board, and answer the questions:
What type of relationship does the graph indicate?
What would be the mass of a gold nugget with a volume of 2.5 cm3?

17. Counting Significant Figures
RULE 1 All non-zero digits in a measured number are significant. Only a zero could indicate that rounding occurred. Number of Significant Figures cm ft lb ___ m ___

18. Leading Zeros
RULE 2. Leading zeros in decimal numbers are NOT significant.
Number of Significant Figures
0.008 mm 1
oz 3
lb ____
mL ____

19. Sandwiched Zeros
RULE 3. Zeros between nonzero numbers are significant. (They can not be rounded unless they are on an end of a number.)
Number of Significant Figures
50.8 mm 3
2001 min 4
0.702 lb ____
m ____

20. Trailing Zeros 25,000 in. 2 200. yr 3 48,600 gal ____
RULE 4. Trailing zeros in numbers without decimals are NOT significant. They are only serving as place holders.
Number of Significant Figures
25,000 in. 2
200. yr 3
48,600 gal ____
25,005,000 g ____

21. Learning Check
1. Which answers contain 3 significant figures? A) B) C) All the zeros are significant in A) B) C) x ,675 rounded to 3 significant figures is A) 535 B) 535,000 C) 5.35 x 105

22. Significant Numbers in Calculations
A calculated answer cannot be more precise than the measuring tool.
A calculated answer must match the least precise measurement.
Significant figures are needed for final answers from
1) adding or subtracting
2) multiplying or dividing

23. Adding and Subtracting
The answer has the same number of decimal places as the measurement with the FEWEST decimal places. This shows the least precise measurement one decimal place two decimal places 26.54
answer one decimal place

24. Multiplying and Dividing
Complete the operation, then round the calculated answer until you have the same number of significant figures as the measurement with the fewest significant figures.

25. Example:

26. Learning Check
In each calculation, round the answer to the correct number of significant figures = A) B) C) = A) B) C) 40.7

27. Learning Check A. 2.19 X 4.2 = 1) 9 2) 9.2 3) 9.198 B. 4.311 ÷ 0.07 =
1) ) )
B ÷ =
1) ) ) 60
C X =
X 0.060
1) ) )

28. Metric System
The metric system is based on a base unit that corresponds to a certain kind of measurement
Length = meter
Volume = liter
Weight (Mass) = gram

29. Metric System Prefixes plus base units make up the metric system
Example:
Centi + meter = Centimeter
Kilo + liter = Kiloliter

30. Metric Prefixes Kilo- means 1000 of that unit
1 kilometer (km) = meters (m)
Centi- means 1/100 of that unit
1 meter (m) = 100 centimeters (cm)
1 dollar = 100 cents
Milli- means 1/1000 of that unit
1 Liter (L) = milliliters (mL)

31. Metric Prefixes

32. Learning Check
m = 1 ___ a) mm b) km c) dm g = 1 ___ a) mg b) kg c) dg L = 1 ___ a) mL b) cL c) dL m = 1 ___ a) mm b) cm c) dm

33. Dimensional Analysis What happens when you divide a number by itself?
What happens when you divide a unit by itself?
In both cases, you get the number 1.
Dimensional analysis involves multiplication and division.
Focus on cancelation of UNITS
A method of unit conversion

34. Conversion Factors
Fractions in which the numerator and denominator are EQUAL quantities expressed in different units. OR

35. Dimensional Analysis Steps:
Read the question!
Write down what you are given.
Write down what you want to know
Decide on a way to get to the desired answer (conversion unit)
Start the conversion by placing the given information over 1

36. Dimensional Analysis Steps
6. Write in the conversion units. Hint: The top unit of the given information should go in the denominator of the conversion unit. 7. Cancel the units.

37. 8. Ask: Is the top unit the desired unit for the final answer
8. Ask: Is the top unit the desired unit for the final answer? If yes, cancel the units and complete the operations (multiplication and division) If no, determine another conversion that will get you to the desired unit.

38. Learning Check 1. Liters and mL 2. Hours and minutes
Write conversion factors that relate each of the following pairs of units:
1. Liters and mL
2. Hours and minutes
3. Meters and kilometers

39. How many minutes are in 2.5 hours?
Example:
How many minutes are in 2.5 hours?

40. Example
A rattlesnake is 2.44 m long. How long is the snake in cm?

41. What is Scientific Notation?
Scientific notation is a way of expressing really big numbers or really small numbers.
For very large and very small numbers, scientific notation is more concise.

42. Scientific notation consists of two parts:
A number between 1 and 10
A power of 10
N x 10x

43. To change scientific notation to standard form…
Simply move the decimal point to the right for positive exponent 10.
Move the decimal point to the left for negative exponent 10.
(Use zeros to fill in places.)

44. To change standard form to scientific notation…
Place the decimal point so that there is one non-zero digit to the left of the decimal point.
Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10.
If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.

45. Examples Given: 0.000567 Given: 289,800,000 Answer: 5.67 x 10-4

46. Example Given: 1.976 x 10-4m Given: 5.093 x 106 m .0001976 m

47. Learning Check Express these numbers in Scientific Notation: 405,789
3,000,000,000

48. Can you hit the bull's-eye?
Three targets with three arrows each to shoot.
How do they compare?
Both accurate and precise
Precise but not accurate
Neither accurate nor precise
Can you define accuracy and precision?

49. Accuracy vs. precision
Accuracy- describes how well the results of a measurement agree with an accepted value Precision- the degree of exactness of a measurement, depends on the instrument used for measurement

50. Express mg in grams

51. Express 0.75 km in centimeters

52. Express 35 km/h in meters per second

53. The smallest living organism discovered so far is the mycolasm
The smallest living organism discovered so far is the mycolasm. Its mass is estimated as 1.0 x g. Express this mass in micrograms.

54. If a metric ton is 1.0 x 103 kg, how many people can safely occupy an elevator that can hold a maximum of exactly one metric ton?

55. Bellwork
The average mass of an automobile is 1.44 x 106g. Express this mass in Hectograms.
2. The distance between the earth and the sun is about 1.5 x 1011 m. Express this distance in kilometers.
3. How many significant figures are in the number: m?
4. Add the following: 16.2 m m
5. Multiply: (6.52 x 1011m) x (4.7 x 10-10m)