Force Vector Lab

Section A:

After setting up the force table as shown by your instructor, attach one of the pulleys to the table somewhere between 180o and 270o. Attach another pulley to the table somewhere between 90o and 180o. Make sure that the two pulleys are greater than 90o apart but not more than 170o. Designate one pulley as “A” and the other as “B” and record their positions. Screw the centering post up so that it catches the ring. Add 100 g to each pulley. Experimentally find the Equilibrant Force (the force that balances the Resultant Force) by attaching the third pulley “C” to the table. Change the mass on the hanger of “C” and its angle until the ring balances in the center of the table. The amount of mass on pulley “C” and the angle at which it balances the other two is the Equilibrant Force.

Section A Data Table:

Pulley / Mass in grams / Angle
A
B
C

Section B:

Repeat the procedures from section A, except vary the amount of mass placed on pulleys “A” and “B” so that each is supporting a different amount of mass. Find the Equilibrant Force by adjusting the mass on pulley “C” and its angle until the ring is centered and does not move when the post is lowered.

Section B Data Table:

Pulley / Mass in grams / Angle
A
B
C

Section C:

In this section you will be asked to find the Equilibrant Force using the algebraic method before putting the pulleys on the table and checking the accuracy of your results. Before putting the pulleys on the table, choose masses and angles for both pulleys “A” and “B” keeping in mind the restrictions in section A. Using both these vectors, “A” and “B”, mathematically find the predicted Equilibrant. Please show your work. Remember that the Equilibrant is a negative resultant. Now put all three pulleys on the table and check to see if your predicted equilibrant is correct. This would be your actual equilibrant. If it does not balance “A” and “B”, adjust pulley “C” until the ring balances and record your actual equilibrant.

Section C Data Table:

Pulley / Predicted Mass in grams / Predicted Angle / Actual Mass / Actual Angle
A
B
C

Vector Lab Questions:

  1. Explain the difference between equilibrant and resultant forces.
  1. What conditions must be met for an object (the ring in this case) to be in a state of equilibrium?

Draw your three vector addition problems (A, B and C) on the protractor above using a different color for each problem.