1.  Open the Worksheet and fill in the header information.

2.  The photogate should be already connected to the DataLogger interface, which is in turn connected to the computer. Open the Picket-Fence application. Move to the Distance vs. Time Graph Window.

Note that all measurements will be made in SI units (m, s, kg).

3.  TEST RUN: Use the mouse to hit the Collect button. The timer will not begin until the photogate beam is interrupted. As a test run, drop the picket fence lengthwise through the jaws of the photogate so that the ruler is as vertical as you can get it. Also practice making a clean release; that is, gently hold the tip of the ruler between your thumb and forefinger and let it suspend itself along the vertical, then smoothly release it so that it falls without wobbling. PLEASE make sure that it lands on the foam cushion to avoid damaging it. Hit the Stop button after the ruler has landed.

4.  The data will be taken automatically, and plots of Distance vs. Time and Velocity vs. Time (magnitude) will be displayed. A TableWindow, with the data tabulated will also be displayed. If either of these windows is missing, select the appropriate one under the WINDOW menu.

5.  Select the Velocity vs. Time window, and under the ANALYZE menu, confirm that Linear Fit is checked. This selection will tell the computer to draw a straight line that best fits the data using a technique called least squares fitting (linear regression), and to evaluate the slope and y-intercept of this line. These results will appear in a data box on the plot. Double click on the Linear Fit data box. In the dialog box, select the Standard Deviation buttons for Slope and Intercept.

6.  MEASUREMENT RUNS: Make 10 drops of the picket fence through the photogate. For each drop, perform the following steps before going on to the next drop:

• From the Table Window, copy the Acceleration data to the Worksheet in the Acceleration Data table at the first cell indicated for each run. These cells are C21:G30 for drops 1 through 5 and cells C56:G65 for drops 6 through 10.

• Record the Slope and its Standard Deviation, and the Y-Intercept and its Standard Deviation (as displayed in the floating information box) on the Worksheet in cells C38:G41 for drops 1 through 5 and cells C71:G74 for drops 6 through 10. If the Standard Deviations do not appear in the box, double click on the box and Check the Standard Deviation buttons in the dialog window.

7.  After the 10th drop is completed, use the handles to expand the Distance vs. Time window so that it fills the entire screen.