1. PowerPoint Tutorial

2.  Once the data collected portion of an experiment is completed, the work of determining the relationship between the variables begins.  Creating a graph of the data is a very effective way of accomplishing this.  The following example will guide you through the creation of graphs as they are used in physics.

3. Example…  A scientist wants to determine the relationship between the time a faucet it left on and the amount of water that flows through it. 1. In this experiment… a. What is the independent variable? b. What is the dependent variable? c. What are some things that could affect this relationship that must be recorded and kept constant? d. What would be a good hypothesis for this lab?

4.  Once the scientist answers the questions in #1, she will collect data. The simulation will demonstrate how the lab will be conducted and the data will be listed in the table below. Copy this data into the table provided. Time (Seconds) Volume (Liters) 00 Example… 5.2 10.4 15.6 20.8 25 1.0 30 1.2

5. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Now that the data is collected we’re ready to make a graph.

6. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Now that the data is collected we’re ready to make a graph. On a piece of graph paper, use a ruler to draw the horizontal and vertical axes.

7. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 On a piece of graph paper, use a ruler to draw the horizontal and vertical axes. Notice that the graph takes up almost all of the page. We don’t want something like this…

8. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Now we add a TITLE. It should include the independent variable, dependent variable, and the object or event being studied. For example… Volume vs. Time for a Faucet

9. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Now we LABEL THE AXES. Write the name of the variable and the units. The INDEPENDENT VARAIBLE goes on the HORIZONTAL AXIS. The DEPEPDENT VARIABLE goes on the VERTICAL AXIS. Volume vs. Time for a Faucet Time (seconds) Volume (Liters) Time (seconds) Volume (Liters)

10. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Volume vs. Time for a Faucet Time (seconds) Volume (Liters) Now we will number the axes. Each axis should start at zero. The scale on each axis must be consistent. This means that the numbers on each axis must increase by the same amount each time. Choose a scale so that the numbers in the data table take up as much of the axis as possible. 0 0 We’ll make every four squares equal to 0.2 Liters Here is a sample scale for the vertical axis. 0.2 L 0.4 0.6 0.8 1.0 1.2 0.2 Note the tick marks that show exactly where each number is.

11. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Volume vs. Time for a Faucet Time (seconds) Volume (Liters) Now we will number the axes. Each axis should start at zero. The scale on each axis must be consistent. This means that the numbers on each axis must increase by the same amount each time. Choose a scale so that the numbers in the data table take up as much of the axis as possible. 0 0 0.4 0.6 0.8 1.0 1.2 0.2 4 8 1216 202428 32 36 Note that the scales on the two axes do NOT have to be the same. To mark every square would be too messy so we’ll mark every other one. On the horizontal axis we’ll make every square equal to 2 seconds.

12. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Volume vs. Time for a Faucet Time (seconds) Volume (Liters) Now we’re ready to start plotting points... 0 0 1.2 1.0 0.8 0.6 0.4 0.2 4 8 1216 202428 32 36

13. Example… Time (Seconds) Volume (Liters) 00 5.2 10.4 15.6 20.8 251.0 301.2 Volume vs. Time for a Faucet Time (seconds) Volume (Liters) 0 0 0.4 0.6 0.8 1.0 1.2 0.2 4 8 1216 202428 32 36 Now that the points are plotted, the last step is to draw a best-fit line. If the points seem to all line up as they do in this graph, use a ruler to draw a straight line that hits as many as possible. If the points seem to show a curved pattern, draw a smooth curve to connect them.