SCIENTIFIC METHOD REVIEW Unit 1

1 ST STEP  Ask a question or present a problem  Can’t experiment if you don’t have a problem.  What would be an example of a question or problem in science?

2 nd STEP  Collect Information  Study, Research, Ask questions, Look at previous studies  Don’t want to do an experiment that has already been done.  Need information before you can decide how to experiment.

3 rd STEP  Form a hypothesis (an educated guess)  Why is it educated?  Why is it important to form an opinion about your problem?  So you know how to experiment and what to look for.  Can your hypothesis be wrong?

4 th STEP  Test the hypothesis with an EXPERIMENT  Independent Variable: One thing you are testing/changing (graphed on the x-axis)  Dependent Variable: Measurable Outcome (graphed on the y-axis)  Control: Has no independent Variable; used to compare to experiment  Constants: all other parts of your experiment that must remain the same in each setup.

5 th STEP  Collect Data & Analyze  Graph all the data  Hard to see patterns of numbers; graphs help  Study, Study, Study to see what your experiment showed

6 th STEP  Draw a conclusion  Prove or disprove hypothesis  If you didn’t find an answer to your question, start with a new hypothesis or change your experiment.

Measurement & Problem Solving Unit 1

Length  The distance between two points  Unit: meter, cm, mm, km  Tool: metric ruler or meter stick

Mass  The amount of matter that makes up an object.  Unit: kilogram, gram, mg, cg  Tool: Triple beam balance  To use balance: Start with 100g bar, then the 10g bar, and finally the 1g bar. Make sure lines match up

Volume (liquid)  The amount of space an object takes up  Unit: liter, mL, kL  Tool: Graduated cylinder  Meniscus is the bottom of the curve; make sure you get on eye level to take measurement

Volume (solids)  Unit: Cubic centimeter (cm 3 )  Tool: ruler (length x width x height)  If it is an irregular shape, drop in graduated cylinder and see how much the water is displaced  1 mL = 1cm 3

DENSITY  Density - the amount of mass in a given volume of an object. 1. density = mass divided by volume 2. basic unit is g/mL for liquids or the g/cm 3 for solid 3. determines if something sinks or floats 4. density of water is 1 g/mL anything higher will sink and lower will float.

Accuracy & Precision  Used to discuss the uncertainties of measured values.  Precision-a measure of how closely individual measurements agree with one another.  Accuracy-refers to how closely individual measurements agree with the correct or “true” value.  Example: Measurements in the science lab

Scientific Notation  To show how very large or very small numbers can be expressed using the power of 10  Move decimal point behind the first whole number  If move to the left, exponent will be positive; if move to the right, exponent will be negative

 93,000,000 becomes  9.3 x 10 7  becomes  x  Examples: Open your books  Page 116 example 5.2

Significant Figures  The numbers recorded in a measurement (all the certain numbers plus the first uncertain number)  Rules for counting significant figures: 1. Nonzero integers always count 2. Zeros: leading zeros never count; captive zeros always count; trailing zeros only if the number is written with a decimal point 3. Exact numbers: numbers not obtained using measuring devices but by counting – these have no limit

Practice Problems  g   x 10 3  110 riders 33 55 44  Unlimited  Page 126 self check

Rules for using Significant Figures 1. For multiplication & division: the number of S.F. in the answer is the same as the smallest number of S.F. in the problem. a x 1.4 =  For addition & subtraction: the smallest number of decimal places in the problem will be used in the answer. a =  31.1

Practice Problems    2.6 x 4.22   0.072/4.36  1 place past decimal  No places past decimal 22 22  Practice probs 129 self check

Metric prefixes kilo (k) = 1000 hecto = 100 deca = 10 root word (meter, gram, liter) deci = 0.1 or (1/10) centi (c)= 0.01 or (1/100) milli (m)= or (1/1000) micro(  )= or (1/1,000,000)  move decimal  km = 5 m=500 cm =5000 mm These values are all equivalent. Example: 5km = _________ m; __________ cm 23cm = _______m; __________km

Conversion factors METRIC-TO-METRIC: (*) can be substituted for meter, gram, or liter 1 k* = ____ * 1 h* = ____ * 1 Dk* = _____ * 1 * = _____ d* 1 * = _____ c* 1 * = _____ m*

Conversion Factors ENGLISH TO METRIC  1 inch (in) = 2.54 cm  1m = 1.09 yards (yd)  1 km = 0.62 miles (mi)  1 kg = 2.2 pounds (lbs)  1 L = 1.06 quarts (qts)  1 Newton (N) = 0.22 lbs

Dimensional Analysis  The use of conversion factors to change from one unit to another. 1. Write down what you know. 2. Draw chart 3. Fill in with conversion factors 4. Multiply across top 5. Divide across the bottom