Static Equilibrium

•   Ensure that there is a vertical pin in the center of your force table.  Place the pin through the largest of the five holes in the stick.  Hang 100 g from one of the four threads tied to the stick, and 200 g from another.  The threads should run over the pulleys and the points of the pulleys should line up with the direction of the threads.  Choose positions for the pulleys such that the threads make at least 15^o angles with the long axis of the stick.
 
•   Open the worksheet for today.  Complete the sketch in Question 2 by moving the vectors and symbols to reflect the forces on the stick from the threads.  Move the origin of the coordinate system to correspond to the position of the pin.
 
•   Record your raw data in the yellow cells of the first table.  Using the protractor, measure the distances (to the nearest millimeter) between the pin and the holes where your two threads are attached.  These are the magnitudes of your position vectors.  Measure the angle (to the nearest half of a degree) that the threads make with the direction of your position vectors.  Measure the two masses (with hangers, to the nearest tenth of a gram) using a mass balance.
 
•   Fill in the first table: Calculate the force magnitudes, force vectors, torque magnitudes, and torque vectors.  Remember that positive torques are ones that would cause counter-clockwise motion.  Sum the torque magnitudes and torques.  Calculate the fractional error by dividing the sum of the torques by the sum of their magnitudes.  If the fractional error is greater than 0.099, redo your calculations or repeat the experiment.  Don’t forget to note your units in the square brackets at the top of each column.