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# Investigation 2 – PostLab

Complete the Focus Question in your SD then discuss it as a class.

### ANALYZE IT

Complete the Analysis Questions in your SDR then discuss them as a class.

Note: You should refer to your data recorded in Table A to answer the following questions.

• Of all of the data recorded during the experiment, only two measurements varied greatly from trial to trial. Which two measurements varied?
• What is the relationship between velocity and frictional force?

One way of observing relationships between variables is to graph the data. You should use the following steps to graph the relationship between frictional force and velocity.

• Draw an x- and y-axis to set up your graph in your Investigation 2 Student Data Record.
• Determine how to label the x- and y-axis. Refer to the Determining How to Label the X-Axis and Y-Axis card in the Procedural Toolbox if necessary. Velocity, the independent variable, should be placed on the x-axis, and frictional force, the dependent variable, should be placed on the y-axis.
• Look at your values recorded in the table. You should next determine the range of numbers that should be included on each axis based on the range of their data. For example, if your values for velocity vary from 120 m/s to 240 m/s, you may wish to provide a range from 100 m/s to 250 m/s on your graph.
• After placing the appropriate numbers along each axis, you should plot their data.
• Once you have plotted the data, you should draw the best fit line through the points on your graph. The best fit line may not exactly connect each point. Rather, the best fit line is a straight line that goes through the midpoint between all of the points.