phy121
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: **
12:47
** 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: **
2.5, 10, 13.5
7.5, 8.4, 8.6
.76, 1.52, 1.9
The first line on the edge of the grid.
I followed the lines across the graphs to the aproximate lenght and then back to the y-axis for the spprox force.
The first lines are where the bands were attached to the rod. The second line is the lenghts of the rubber bands, starting from the left side of the rod across.
The third line is the force applied at each point on the rod, from left to right.
** Net force and net force as a percent of the sum of the magnitudes of all forces: **
I came up with an approximate Fnet of .38N.
B = 14%
A = 52%
C = 34%
The first line is the difference in forces pulling the rod up and pulling it down. I attribute this not being 0 to error in finding forces. The next three lines are the percentages of the total force the bands/band systems are appling to the rod.
If one of the rubber band systems A, B, C is consists of two rubber bands, then you need to find the total force of the two rubber bands in that system.
** Moment arms for rubber band systems B and C **
7.5cm
3.5cm
These are the moment-arm locations of the outter rubber bands with reguard to the center system. I simply measured the lengths.
** Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C. **
3.04, 12.16, 7.6
7.5, 3.5
The top line is the length of the force vector of each rubber band system, in order of B, A, C.
The second line is the lenght at which each vector B and C are located in relation to vector A.
** Torque produced by B, torque produced by C: **
5.7N*cm, -6.65N*cm
These are the resulting torques that each system B and C are applying to the rod. Again, we see some difference. I would assume that this is due to my estimation of forces using my force/distance graphs.
** Net torque, net torque as percent of the sum of the magnitudes of the torques: **
-.95N*cm
7%
I took the net torque value and divided it by the sum of the two torques.
This is the calculated net torque on the rod and its percentange of the total torque applied to the rod.
** 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? **
~1hr
** Optional additional comments and/or questions: **
&#Good responses. See my notes and let me know if you have questions. &#