Your work on torques 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:
.3, 7.15, 11.05
8.15, 11, 9.65
.2N, 3.3N, 2.53N
left-most end of the rod
Looking at the graph that Excel produced, it was estimated by the indicating line. Polynomial.
Net force and net force as a percent of the sum of the magnitudes of all forces:
.57N
9.5%
Moment arms for rubber band systems A and C
6.85, 3.9
Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C.
.8, 13.2, 10.12
6.85, 3.9
Torque produced by B, torque produced by C:
+1.37, -9.867
Net torque, net torque as percent of the sum of the magnitudes of the torques:
76%
Forces, distances from equilibrium and torques exerted by A, B, C, D:
1.26, 0, 0
-2.06, 1.85, -3.8
-0.35, 10.05, -3.52
0.25, 13.95, 3.49
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:
-.9N
they should equal zero, and the magnitudes of the vector length for A and D should be equal to that of B and C
Net torque for given picture; your discussion of whether this figure could be accurate for a stationary rod:
6
no, it should be closer to zero.
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:
-3.738
.9, 3.92
23%
3.738, 10.713, 35%
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:
-14.33
1.51, 6.16
24.5%
14.33, 34.38, 41.7%
In the second setup, were the forces all parallel to one another?
yes
Estimated angles of the four forces; short discussion of accuracy of estimates.
88 degrees
fairly accurate estimates.
x and y coordinates of both ends of each rubber band, in cm
-6.95, -11.2, -6.95, -2.6
-.2, 2.6, -2.05, 11.8
9, -12.05, 5.75, -2.75
Lengths and forces exerted systems B, A and C:.
8.6, .4
9.38, 4.12
9.85, 2.35
Sines and cosines of systems B, A and C:
-1, 0
.98, -.2
-.94, .33
Magnitude, angle with horizontal and angle in the plane for each force:
.4, -90, 270
4.12, 78.6, 101.4
2.35, -70.6, 289.4
inverse tangent to find the angles
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):
0cm, -1.6cm, 0, -.4, 0, -.4
-3.35cm, 16.1cm, -0.8375, 4.025, -0.81, 4.04
3.15cm, -8.9cm, .7875, -2.225, .78, -2.22
Sum of x components, ideal sum, how close are you to the ideal; then the same for y components.
-0.03, 0, .03
1.42, 0, 1.42
Distance of the point of action from that of the leftmost force, component perpendicular to the rod, and torque for each force:
0, .4, 0
6.75, 4.04, 27.27
12, -2.22, -26.64
Sum of torques, ideal sum, how close are you to the ideal.
.63, 0, .63
How long did it take you to complete this experiment?
6hrs
Optional additional comments and/or questions:
It seemed odd that even though the third one gave me the most trouble, it came out to have the most ideal results.
It is not unusual for the most complex setup to give the best results.
Good work throughout.