Day 11: Recap of all our Data

Today was a short day after presentations.  Shivani and Jan Mark completed calculations of Tuesday's data which is summarized in the table below.

 
Effects of Rotating Camera Stand Front, Back and to One Side


Material Back Pitch Forward Pitch 20o Rotation math vertical 30o Rotation math on spot
Lead 9.74 9.61 9.61 9.13 9.61
9.84

9.78 9.58 9.79 9.24 9.55




9.73 9.22 9.62

Steel 9.62 9.63



9.83

9.65 9.58




Golf 9.62 9.48 9.4
9.68 8.71 9.6

9.65 9.43 9.43
9.55
9.59
Wood 9.52 9.4



9.67

9.45 9.38



9.59
Plastic 8.83 8.48



8.98

8.77 8.48




Ping Pong 8.44 8.31





8.33 8.13





 The last column, "on spot", shows the data for which exceptional care was taken to prevent the systematic errors which we have been studying:  dropping the ball exactly even with the length calibration meter stick, making sure the meter stick is not warped and keeping the camera completely level.  The first 2 columns show the effects of pitching the camera stand back and forward by putting a 50 g mass disk under the 2 front legs in the first case and under the single back leg in the latter.  This results in a slightly greater pitch angle for the back pitch than the forward pitch which, as expected, gives a slightly greater pitch angle when pitched forward as seen in the measured values of g closer to the accepted value when the angle is smaller.  The length of the meter stick as seen in the capstone program serves as the length calibration, but due to the pitch of the camera, the actual length, l, as seen in the figure below is measured as the shorter length, l', in the Capstone program, resulting in a smaller value for g.
 
As shown yesterday, the error due to rotation of the camera in the plane is corrected by rotating the axes in the Capstone program.  From careful observation of the video clips, in the cases that the measured g value is higher or lower than expected, the ball has landed just slightly in front of or behind the tape marking the meter stick position.  Since this seems to be the most difficult part of the experiment to perfect, more films will be made on Monday to determine the best techniques for dropping the ball exactly even with the calibration meter in an easily reproducible manner.
































































































































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