 The scientific method comes in many different forms but always has these basic steps: 1. Ask a question 2. Develop a hypothesis (An if/then statement describing what you think will answer the question) 3. Design an experiment 4. Analyze data and draw conclusions

 Let’s do a real world example:  Timmy is a geek and is having a hard time making friends…  He just wants to be friends with the cool kids…

 So Timmy decided to use the scientific method: 1. First he asks his question: “How can I be a cool kid?” 2. Then he develops a hypothesis – an if/then statement that should answer his question or solve his problem. “If I take showers every day, then I can be friends with the cool kids!” 3. He designs an experiment: “I’ll take a shower every day and record how many words the cool kids say to me each day.” 4. He performs his experiment for a certain amount of time and records all his data.

 So Timmy decided to use the scientific method: 4. He analyzes his data and draws conclusions:  He made a graph to display his results:  There is a direct relationship between how many days he showers and how much the cool kids talk to him!

 Now he can draw a conclusion based on his data: Timmy concluded that he is now cool and is friends with the other cool kids!

 In any experiment, it is important to identify the variables that are being affected or kept the same. There are three types: 1. The Independent Variable This is the what you change to see what will happen. Example: For Timmy this was how many days in a row he took a shower. 2. The Dependent Variable This is what you hope is affected by the Independent Variable. Example: How many words a day the cool kids say to Timmy. 3. Constants This is everything that was not a part of the experiment but needed to be kept constant. Example: even though Timmy showered, he still never put on deodorant or stopped playing video games for 12 hours a day. Those variables were held constant.

Remember: This should all be a REVIEW!

 Graphs have 2 axes: the horizontal (usually called ‘x’) and the vertical (usually called ‘y’)  Graphs will be named according to what is plotted (it goes by the general form “Y” vs. “X”  Each axis should always be labeled and include the proper units.

 Lines The general equation for a line is: y = mx + b (where y is the dependent variable, x is the independent variable, m is the slope, and b is the y-intercept) Slope  The equation for slope is

 What is the slope of the line in the graph?  Slope (m) = (∆y / ∆x) m = (y 2 – y 1 ) / (x 2 – x 1 )  First, select two points that are far apart  Plug values into the equation: m = (30 – 10) / (14 – 4) m = 2  So, the slope is 2, but what are the units, and what do they mean?  In this case, the units would be (smiley faces / puppies) or /p  And this tells us that you would get 2 smiley faces for every puppy you see!

 What is the y-intercept of the graph and what does that mean? The y-intercept is 2 and it means that even with 0 puppies you can have a happiness of 2  What is the mathematical representation (equation) for our graph? y = mx + b y = 2x + 2 or H = 2P + 2

 Identifying relationships between variables is crucial in physics.  Two variables are said to be directly proportional when they are each affected in the same way as the other when multiplied by a constant. For instance, in the equation y = kx, y and x are directly proportional because if you were to double y, x would have to double as well.  Two variables are said to be indirectly proportional when one variable is affected inversely when the other is multiplied by a constant. For instance, in the equation y = 1/x, y and x are indirectly proportional because if you were to double x, y would be halved.

 Two variables are said to be directly related when one variable increasing causes the other to increase as well.  Two variables are indirectly (inversely) related when one variable increasing causes the other to decrease.