CHAPTER 0

Scientific Method and Measurement

The Method

What organized method do scientists use to solve a problem?

The scientific method1. Define the problem2. Make a hypothesis3. Make observations4. Record data5. Review the data6. Modify hypothesis7. Retest

The Method

What is the definition of…

1. Hypothesis?

2. Variable?

3. Control?

4. Qualitative Data?

5. Quantitative Data?

A prediction or guess

What changed

Stays the same

Non-numerical (ex. Blue)

Numerical (ex. 55 cm)

The Method

Why is it important not to have too many variables?

Hard to tell which, if any, variables affected the result

Limit the variables and have lots of controls

Theory vs. Law

What is the main difference between a theory and a law?

A law is a (mathematical) relationship that predicts what happens and is always correct.

A theory is an evolving body of information. It has not been proven correct.

Airplane Challenge

I challenge your team to build a paper airplane that will FLY the farthest distance.

Each team will build three planes. 3 pieces of paper, 6 paper clips, scissors

Your team will test ONE variable to see which of your three prototypes will work the best.

In your observations, you must list at least 3 controls and 1 variable.

Airplane Challenge

Before you fly! What am I testing? What is my first

hypothesis? What are 3 controls

and my 1 variable?After you fly! What did I observe

after the test flights?

Please answer these questions in your notebook.

Precision vs. Accuracy

What is the difference between precision and accuracy?

Accuracy refers to how close it is to the correct value

Precision refers to how close together a group of measurements are to each other

Precision vs. Accuracy

On the right hand side of your notes, please draw the following targets with the bullet holes.

Precision vs. Accuracy

Label the target that is accurate and precise.

Precision vs. Accuracy

Label the target that is the least precise.

Precision vs. Accuracy

Label the target that is precise and inaccurate.

Practice Problem #1

An archer shoots three arrows at a target and each land within 1 cm of each other, but none of the arrows are within 30 cm of the center.

Explain whether the archer is precise, accurate, neither or both.

Practice Problem #2

The table lists the results of temperature measurements of a beaker of boiling water. The temperature of boiling water is 100 °C.

Explain whether each thermometer was accurate, precise, neither or both.

Precision and Measurement

1. Pick the measuring device that makes the most sense: stick, book or paper clip

2. Measure the object or area.

3. Estimate the final value. (ex. 0.5, quarter, 1/3)

4. Record your measurements in the table.Object or Area Estimated

Measurement

Stick, Book or Paper Clip

Width of the Lab Area (cabinets to cabinets)

Length of a Desk (long ways)

Height of a Classroom Door

Height of a Lab Bench

The Depth of a Conceptual Science Book

Precision and Measurement

Which measurement do I feel is the most precise and WHY?

What is one benefit AND one drawback to using a smaller unit of measurement?

Scientific Notation

What is scientific notation?

A shortcut for writing really large or really small numbers

Every number can be represented by a number between 1 and 10 and multiplied by a power of 10

Scientific Notation

What are some examples of scientific notation?

Large numbers 190,000,000

1.9 x 108

Small number 0.000567

5.67 x 10-4

Scientific Notation

How do I do scientific notation?

1. Put a decimal after the first non-zero number

2. Count the number of spaces the decimal place moved

3. If the decimal moved to the left, the exponent is positive and if it moved to the right its negative

4. Drop unwanted zeros

Scientific Notation

What is 35600 in scientific notation?

What is 0.000721 in scientific notation?

3.56 x 104

Zeros at the end dropped

7.21 x 10-4

Zeros at the beginning dropped

Scientific Notation Practice

Please convert the following into proper scientific notation:a) 784000b) 100c) 0.023498d) -4321e) 0.0000006f) 1.30

a) 7.84 x 105

b) 1 x 102

c) 2.3498 x 10-2

d) -4.321 x 103

e) 6 x 10-7

f) 1.30

Scientific Notation Reversed

Please convert the following into standard format:a) 5.68 x 103

b) 2.1 x 10-5

c) 4.309 x 102

a) 5680b) 0.000021c) 430.9

Scientific Notation and Calculators

What buttons are used on a calculator for scientific notation?

Its usually either… EE -or- exp

Scientific Notation and Calculators

What may show up on my screen?

On your screen, you may see the following: X10 exponent E exponent (space) exponent

Scientific Notation and Calculators

Put the following number into your calculator and hit equals/enter:

4.56 x 1015

Please understand that you will need to translate this into proper notation!

Scientific Notation and Calculators

Using your calculator, determine the following answers in scientific notation:

Multiply:a) (4.57 x 10-3)(2.0 x 105)

Divideb) (3.1 x 103)/(4.7x105)

a) 914

b) 0.0066

Scientific Notation

What power are you multiplying and dividing by each time you move a decimal?

Powers of 10 These powers

allow us to comprehend very large (size of galaxies) and very small (size of atoms) numbers

Dimensional Analysis

Why is dimensional analysis important?

It allows us to easily convert between units using a series of equivalent fractions

Dimensional Dominoes - Colors With your team, set up the color

dominoes to convert the following colors into new ones.1) Convert cowpoke brown to deeply red2) Convert cowpoke brown to pink glitz3) Convert black leather to orange sizzle4) Convert orange sizzle to black leather5) Convert cowpoke brown to Houdini

blue

Dimensional Dominoes - Units The English unit, the rod, is equal to 16.5

ft. What is this length expressed in meters? Directions: With your team, set up the unit

dominoes to convert the following units into new ones then copy the set-up into your notes (right side).

Answer = 5.03 meters

Dimensional Dominoes - Units The portage trails on maps are

measured and marked in rods. On a recent canoe trip to the Skagit and Cascade Rivers my brother and I portaged a total of 2342 rods. How many total miles did we carry our gear? Directions: With your team, set up the unit

dominoes to convert the following units into new ones then copy the set-up into your notes.

Answer = 7.3 miles

Dimensional Dominoes - Units If a college student smokes an average

of 10 cigarettes per day for five years of school, how much money will they have spent on smokes by the time they graduate? Directions: With your team, set up the unit

dominoes to convert the following units into new ones then copy the set-up into your notes.

Answer = $ 4106.25

Dimensional Dominoes - Units The weight of bullets and arrows is

measured in a unit called the grain. If an arrow weighs 330 grains what is its weight in ounces? Directions: With your team, set up the unit

dominoes to convert the following units into new ones then copy the set-up into your notes.

Answer = 0.775 ounces

Dimensional Dominoes - Units Assuming that you attend school 180 days

a year for 8 hours a day from first through twelfth grade, you’d be in class for a total of 2160 school days. How many total years of your life will you have spent in school by the time you graduate? Directions: With your team, set up the unit

dominoes to convert the following units into new ones then copy the set-up into your notes.

Answer = 1.97 years

Dimensional Dominoes - Units How many pounds does a 5 gallon pail of

water weight? Directions: With your team, set up the unit

dominoes to convert the following units into new ones then copy the set-up into your notes.

Answer = 41.62 pounds

Dimensional Analysis

What is a base unit?

What is a prefix?

Basic unit from which all other units are created Ex. Length – meters Ex. Mass – grams

Goes in front of a base unit to indicate how many Ex. Length – kilometers Ex. Mass – milligrams

Dimensional Analysis

How many different types are there?

Three types: Two step - converting

to or from a base unit Ex. m to km

Three step - converting from a non-base unit to a non-base unit Ex. mm to km

Non-metric – converting between different scales

Dimensional Analysis - Two Step

Please convert 5 kilograms to grams.

First fraction is what we have:

Second fraction is what we want:

Remember… The unit with the prefix gets the one!

Multiply across the top and bottom and then divide.

Dimensional Analysis - Two Step

Please convert: 2.5 cm to m 0.04 J to kJ 3.5 g to mg 0.5 L to cL 3.1 x 104 mL to L 50.8 g to ng

Dimensional Analysis - Three Step

Please convert 92 kilograms to milligrams.

First fraction is what we have:

Second fraction is the conversion to the base unit:

Third fraction is what we want:

Calculate the same way as before

Dimensional Analysis - Three Step

Please convert: 36.0 cm to km 52 kg to mg 601 mL to cL 0.003 dg to cg 8 μg to mg

0.00036 km 52000000 mg 60.1 cL 0.03 cg 0.008 mg

Dimensional Analysis – Non-metric

What is a non-metric conversion?

Use math formulas Ex. Temperature

Use other equivalencies Ex. 12 inches = 1

foot

Dimensional Analysis – Non-metric

Please convert: 34 inches to feet 2 atm to Pa 15 °C to °F 5 L to gallons 2000 calories to J

2.8 ft 202650 Pa 59 °F 1.32 gallons 8368 J