Your 'torques' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Your optional message or comment: **
** Positions of the three points of application, lengths of systems B, A and C (left to right), the forces in Newtons exerted by those systems, description of the reference point: **
0.46, 7.91, 12.18
8.12, 8.53, 8.59
1.25, 3.29, 2.13
The first grid line left of the band 'B' connection was used as the origin.
I used the calibration graphs' equations to determine the above forces - for band 'A' the sum of the calculated forces of the two bands was computed.
These are the forces of the system which are in balance. We will now use torques to determine the accuracy of our measurements.
** Net force and net force as a percent of the sum of the magnitudes of all forces: **
-0.09 N
1.4%
-1.25+3.29-2.13 = -0.09N
** Moment arms for rubber band systems B and C **
7.43, 4.27
These are the moment arms of the forces at points B & C
** Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C. **
5.00, 13.16, 8.52
7.43, 4.27
These are scalar quatities of the above resultant forces and their points of application from the fulcrum.
** Torque produced by B, torque produced by C: **
+9.29, -9.10
These are the torques applied to the bar about the fulcrum at point C (in cmN)
** Net torque, net torque as percent of the sum of the magnitudes of the torques: **
0.19
1.03%
.19/18.39 = 0.0103 is the equation used to determine the percentage of error of magnitude.
** Forces, distances from equilibrium and torques exerted by A, B, C, D: **
1.34, 0.66, 0.88
3.16, 1.47, -4.65
11.42, 0.75, -8.57
0.63, 15.91, 10.02
Forces, their distances from equilibrium and their torques, in comma-delimited format with one torque to a line, in the order A, B, C and D
** The sum of the vertical forces on the rod, and your discussion of the extent to which your picture fails to accurately describe the forces: **
-0.25
I am not sure how it can be assumed the diagram does not accurately reflect the system. We must be discussing the fact that the resultant force is not zero and thus would reflect acceleration in the system.
Your picture is not a diagram, it is a scale model of the observed forces. Due to experimental error, it is unlikely that either your data or a scale model will in fact result in a net force of zero.
However it's clear that you understand this and the implications for equilibrium.
** Net torque for given picture; your discussion of whether this figure could be accurate for a stationary rod: **
-2.32
An accurate measurement and sum of torques would have to sum zero to reflect the conditions of a stationary rod. Any imbalance would result in acceleration
More specifically, in an angular acceleration.
** For first setup: Sum of torques for your setup; magnitude of resultant and sum of magnitudes of forces; magnitude of resultant as percent of sum of magnitudes of forces; magnitude of resultant torque, sum of magnitudes of torques, magnitude of resultant torque as percent of the sum of the magnitudes: **
-3.66-8.07+9.61 = -2.12
0.25, 4.19
5.97%
2.32, 13.28, 17.47%
** For second setup: Sum of torques for your setup; magnitude of resultant and sum of magnitudes of forces; magnitude of resultant as percent of sum of magnitudes of forces; magnitude of resultant torque, sum of magnitudes of torques, magnitude of resultant torque as percent of the sum of the magnitudes: **
0.79
0.00, 6.26
0%
0.79, 47.73, 1.66%
** In the second setup, were the forces all parallel to one another? **
The forces were all parallel, the threads of the rod allowed the clips to remain in place on the rod without slipping. The rod itself was canted approximately 2 degrees clockwise. These factors allowed the system to reach equilibrium.
** Estimated angles of the four forces; short discussion of accuracy of estimates. **
All were 88 degrees (approximately). I used a protractor to determine the angle.
** x and y coordinates of both ends of each rubber band, in cm **
** Lengths and forces exerted systems B, A and C:. **
** Sines and cosines of systems B, A and C: **
** Magnitude, angle with horizontal and angle in the plane for each force: **
** x and y components of sketch, x and y components of force from sketch components, x and y components from magnitude, sine and cosine (lines in order B, A, C): **
** Sum of x components, ideal sum, how close are you to the ideal; then the same for y components. **
** Distance of the point of action from that of the leftmost force, component perpendicular to the rod, and torque for each force: **
** Sum of torques, ideal sum, how close are you to the ideal. **
** How long did it take you to complete this experiment? **
150min
** Optional additional comments and/or questions: **
Excellent work. See my notes for a couple of possible clarifications.