phy 121
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: **
1cm, 6.75cm, 13.7cm
7.7cm, 7.8cm, 8.3cm
.76N, .76N, 1.9N
Isn't one set of rubber bands doubled?
from left end of line
I obtained the Newtons by referring to the graph used in the rubber band calibration lab.
The 1st line contains the measurements from the left end of the bar where the lines intersect. The 2nd line contains the measurements from the lengths of the rubber bands. The 3rd line contains the Newtons.
** Net force and net force as a percent of the sum of the magnitudes of all forces: **
-1.9N
-2%
I divided the sum by 100 to get -2%.
** Moment arms for rubber band systems B and C **
6.3cm, 4cm
These are the distances between rubber band b to c and from a to c, I measured with a ruler.
** Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C. **
3.04cm, 3.04cm, 7.6cm
6.3cm, 4cm
The 1st line contains the lengths of the vectors by multiplying the Newtons by 4cm. The 2nd line contains the distances from the fulcrum to points of the applications (b & c).
** Torque produced by B, torque produced by C: **
-4.8, -7.6
I obtained the numbers above by multiplying the newtons (-) by the length of the moment-arm.
** Net torque, net torque as percent of the sum of the magnitudes of the torques: **
-12.4
-1%
I divided the sum by 100 to get -1%.
The 1st number shows the net torque used in the system. The 2nd number shows the 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? **
45 min
** Optional additional comments and/or questions: **
&#This looks good. Let me know if you have any questions. &#