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, 14), (7, 14), (14, 14)
9.5, 9.0, 8.5
18.1, 17.1, 16.2
(0, 14)
I multiplied .19 times the number of dominoes 10 and then by each individual measurement of length.
The first line is simply the point on the graph where the three points and the vertical lines intersect the horizontal line. The second line is the measurements of the bands. The third line is the force in Newtons.
If your rubber band lengths were those required to support 10 dominoes, then each force would be the weight of 10 dominoes, or 1.9 Newtons. There is no reason to multiply anything by the length of a rubber band. The length of the rubber band gives you only the force exerted by that rubber band; to get that force you would use the graph you made for that rubber band in the calibration experiment.
However
** Net force and net force as a percent of the sum of the magnitudes of all forces: **
51.4
5.71
Magnitude was done by taking the square root of each length and dividing 51.4 by the sum of the magnitudes. I do not believe that this is correct.
&#To get the net force you add the forces. If the upward direction is chosen to be the positive direction, the forces exerted by the two rubber bands at point A are positive, the forces exerted by the rubber bands at B and C are negative. &#
** Moment arms for rubber band systems B and C **
6.5 cm, 7.5 cm
These are just the distances between each point.
** Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C. **
9.5, 9.0, 8.5
2.0, 2.0
The numbers in the second line are the distances between the fulcrum and the point that force is applied.
** Torque produced by B, torque produced by C: **
-.5
+.5
The length in B is 9.5, A is 9.0 and C is 8.5.
You haven't explained what your torques mean or how you obtained them.
** Net torque, net torque as percent of the sum of the magnitudes of the torques: **
-.5 + .5 = 0
0%
0 of a percentage gives 0%.
The -.5 was from C and + .5 from B so you add them together to get 0 and 0 percentage.
** Forces, distances from equilibrium and torques exerted by A, B, C, 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: **
** Net torque for given picture; your discussion of whether this figure could be accurate for a stationary rod: **
** 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: **
** 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: **
** In the second setup, were the forces all parallel to one another? **
** Estimated angles of the four forces; short discussion of accuracy of estimates. **
** 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? **
40 mins
** Optional additional comments and/or questions: **
This report will require significant revision. See my notes and be sure they have answered the questions you have posed here. Then let me know if you have additional questions about any of these calculations or concepts.