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:
Net force and net force as a percent of the sum of the magnitudes of all forces:
Moment arms for rubber band systems A and C
Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C.
Torque produced by B, torque produced by C:
Net torque, net torque as percent of the sum of the magnitudes of the torques:
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?
Optional additional comments and/or questions:
Dr. Smtih,
I have read through the instruction for first experiment several times, I have setup the system just like the instruction say, but my set up goes beyond the piece of plywood. The bottom hooks of Rubberbands B and C are dangling off the end of the plywood. I dont know if my setup is wrong or what, but if I stretch Rubberband C to 12.38cm. (length from calibration at 10 dominoes) it would be way off the piece of plywood. I am also certain that my etup is right, because it looks identical to your picture of the setup, mine is just bigger. Please let me know what I should do. Thank You
If the board is too narrow to place a hook at the very end of the rod, then adjust the distances inward a bit.
As to the top-to-bottom-distance problem:
Can you bend the hooks to make them shorter? One end of the top hook could even be bent around the board rather than being fixed with a paper clip.
Be sure the board is in the position where the long side is parallel to the y axis. The board should be at least 25 cm on this side, and this should be enough to accomodate the system.
If not, adjust other quantities (e.g., the number of dominoes to which the length of the band corresponds) so the setup can fit on the board.