Phy 201
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: **
3cm, 10.5cm, 20.5cm
8.5cm, 8.5cm, 8.0cm
6.5N, 14.53N, 4.75N
the left end of the line which was 3cm before the first rubber band
I used my calibration graphs to determine how many cm corresponded to a Newton and then found the Newtons applied based on this graph.
These results show the force in Newtons that each rubber band was acting on the bar.
** Net force and net force as a percent of the sum of the magnitudes of all forces: **
3.28N
13%
These results mean that the upwards force was 3.28N larger then the downward forces.
** Moment arms for rubber band systems B and C **
7.5cm, 9.5cm
These numbers represent the moment arm for B 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. **
26, 58.12cm, 19cm
-30cm, 38cm
These numbers are representative of the actual scale diagram of the rod.
** Torque produced by B, torque produced by C: **
45.125, -48.75
These are the torques for my B and C rubber band systems.
** Net torque, net torque as percent of the sum of the magnitudes of the torques: **
-3.63
3.8%
This represents my experimental error. The rod was not in equilibrium and actually had a negative torque of -3.63. This was almost 4% error.
** Forces, distances from equilibrium and torques exerted by A, B, C, D: **
7.02, -13.5, -94.77
5.09, -5.96, -30.36
8.93, 8, 71.44
6.55, 10, 65.5
** 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: **
0.45
My picture seems to depict the forces fairly well. My net force is close to 0, if anything it would be pulling up on the right.
** Net torque for given picture; your discussion of whether this figure could be accurate for a stationary rod: **
The net torque is 2 so it should move clockwise slightly.
My picture could be close, but the rod would be tilted slightly clockwise so it wouldn't be stationary.
** 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: **
-19.46
27.59, 10.35
3.5%
11.81, 262.07, 4.5%
These results describe the magnitudes of my picture
** 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: **
19N
8, 38.6
22%
9%, 209
These represent the forces for my tilted picture.
** In the second setup, were the forces all parallel to one another? **
No, I would say the degrees vary by about 10 degrees. I made the estimates pretty much based on the visual. One of my vectors seems to be tilted slightly.
** Estimated angles of the four forces; short discussion of accuracy of estimates. **
90, 90, 95, 85
I made the estimates based on what I saw. I think they arent very accurate but this is what it seemed. I am sure the 90 degrees shifted slightly, the top (B) to the left and A to the right.
** 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: **
The set up for the second part of this experiment is basically impossible in my opinion. I tried to make it work but I'm sure the data shows how much trouble i had setting this up. It was definitely frustrating.
Very well done, despite the frustration. Your data are much better than most, among the best I've seen.