26 Procedure

Conduct the following steps for each of your three chosen balls until a good reading is provided two times for each ball.

1.   In the Capstone program, click RECORD in the bottom left while the desired ball is suspended from the Drop Box above the motion sensor (If the ball is not properly suspended from the Drop Box, please refer to the DROP BOX SETUP section). On the position vs. time graph, a position of about 75-90 cm should be showing with minimal fluctuations. If there are large fluctuations or it is not reading a constant value at about 75-90cm, try the following techniques to ensure it is properly tracking the ball:

a.   Readjust the sensor until this position is shown without any fluctuations for 5-10 seconds. When the position signal is stable at about 75-90 cm, cover the sensor with the sensor guard and check that the position on the graph is still about 75-90 cm. Note: The sensor guard may interfere with the motion sensor, so make sure the program is accurately tracking the desired ball.

b.   Check to see that the cardboard end of the ball is parallel to the motion sensor. If it is at an angle relative to the ground, this could be intruding on the motion sensors detection. For instructions on how to set up the ball, refer to the BALL SETUP section.

c.   Ensure the ball is not swinging or oscillating to a large degree. This will mainly be an issue with the balls that are suspended by staples.

d.   If all of the previous techniques failed, call a TA over to examine the setup.

Once your ball is initially shown to have a height of about 75-90 cm on the program for a reasonable amount of time with the guard set up, you can stop recording and delete that run. This part of the procedure is to ensure the ball is starting at a consistent initial height and that the motion sensor is correctly detecting the ball.

2.   Now we will begin with the actual experiment. Click RECORD and observe the position versus time graph. If it is at a position of about 75-90 cm with minimal fluctuations for about 5 seconds, press the Timer Switch button to release the ball.

3.   Decide if the run is good.

a.   Examine the position versus time graph. If you do not have a smooth curve before and during the fall, reposition the sensor slightly and repeat steps 1 and 2 (use the Delete Last Run button at bottom of screen to delete any bad runs).

b.   Examine the velocity versus time graph. It may generally have some glitches looking like little z’s in the data. This happens when there is a small error in the position at one point. This causes one speed to be high and the next to be low (or vice versa). If there are any high “jumps” on the run, you should delete the run and do it over.

c.   If you are still unsure, you can ask the TA whether your run is good enough for further analysis.

**IMPORTANT** Save your experiment as you go by clicking “File > Save Experiment”. This will prevent any possible loss in time if something unexpected happens.

4.   When you have a good run, mark all the points on both the position and velocity graphs that are after the ball hit the guard and delete them. To do this efficiently:

a.   Left click on a data series on the graph, then, in the top toolbar, select the option “Highlight range of points in active data” (this icon looks like a series of highlighted points) and cover the highlighted box over the desired data to be deleted. You can move and resize the box as needed. Then right click the highlighted box and select “Deletions->Delete Highlighted Data Points”.

b.   Then open Data Summary (left of the graph), double-click on the run under one of the properties and re-label it based on the type of ball dropped. This will automatically change the labeling of the data points for every graph. Click Data Summary again to close it. Reminder: use a descriptive name so that your ball can be easily identified by the grader.

5.   Label this run in the bottom left corner of your graphs with the title: “[ball name] #” where # is the current run number for that ball.

6.   Select the entire graph area, then click the “copy” button in the very top toolbar under Edit. Create a new tab by selecting the “Add Page” option just above “Tools” on the left hand side. In the new tab click “paste” in the very top toolbar under Edit to paste your three graphs. Relabel the tab with the same title you gave the graphs earlier (i.e. [name] #).

** Important ** Under this new tab, select the properties icon from the graph toolbar, then Data Options, then deselect both “Show New Runs” and “Show New Runs From Prior Pages”.  This will allow that tab to store any of the previous runs you had without it being overwritten by the latest run.

7.   You will repeat this procedure for each run such that you have a different tab within Capstone for each of your runs.

** WARNING ** After every successful run, SAVE YOUR CAPSTONE FILE by selecting “File > Save Experiment”. This is to prevent any loss of information if something unexpected happens. 

Once you have finished this step in the procedure for your FIRST run, ask the TA to come over and check that you did the procedure correctly.

CHECKPOINT

(Ask the TA to check your three plots for the FIRST run. Once your graphs have been approved by the TA, move onto the steps below)

8.   Go back to the original tab (by default it is named “Page #1”) and repeat steps 1-7 until you have two good runs for each of the three balls.

Note: You can also pull data from previous runs onto a new tab by performing the following steps:

A.  Click New Tab (page button above “Tools”).

B.  Click and drag the “Graph” icon from the right-hand side under “Displays” onto the tab.

C.  Open “Data Summary” and click and drag each property for your run onto the graph area.

** Note ** The current run will always appear under Page # 1. Make sure you go back to this tab before starting each new run. 

** Cautionary note **  When selecting ‘delete last run’, this will delete it from every tab. Only select this button after a run that is bad. If you accidentally delete a run you didn’t intend to, you can always undo this by pressing ctrl+z.

Save your experiment as you go by clicking “File > Save Experiment”.