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: **
1.3cm, 7.7cm, 12.6cm
7.6cm, 8cm, 8.4cm
.38N, 1.14N, 1.52N
(-7cm,0) (0,0) (5.2cm,0) The refrence point
Honestly, I used the data from the rubber band calibration lab.
good; that's what you were supposed to do
The lengths were determined by what was required to make the metal rod be horizontal given force being pulled down at different points.
** Net force and net force as a percent of the sum of the magnitudes of all forces: **
-.76N
25%
This is the amount of force pulling the system down and what percent of the total force this downward pull is.
One of those rubber bands was doubled. Did you account for that?
** Moment arms for rubber band systems B and C **
5.7cm, 5.3cm
I measured from the middle to the points that the hooks rested on
** Lengths in cm of force vectors in 4 cm to 1 N scale drawing, distances from the fulcrum to points B and C. **
2.3cm, 1cm, 3.5cm
1cm, 1.2cm
This is a scale representation of the forces acting on the metal rod.
** Torque produced by B, torque produced by C: **
-2.66, 7.9
I multiplied the distance from the refrence point the force was and the force in N to get the torque.
** Net torque, net torque as percent of the sum of the magnitudes of the torques: **
5.24
49.6 percent
First line I simply added the torques. Second line, I divided the sum of the toques by the absolute value of the torques added and multiplied by 100.
This is the total torque on the system and how much the actual torque is relative to the total in the system.
** 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? **
45min
** Optional additional comments and/or questions: **
&#Your work looks good. Let me know if you have any questions. &#