General Physics Lab: Equilibrium of Vector Forces

Equipment and setup

• We will use the following equipments to examine various vector forces in equilibrium: force table ( see Figure 1), three pulleys, three mass hangers, masses, protractor ( Figure 7).
• Do not tie knots in the string, in stead, wrap the free end of the string through the slot in the weight hanger to attach it. Also level strings by adjusting the pulley height (Figure 2).
• The masses are of various weights (three each): 100, 50, 20, 10, 5 and 2g (see Figure 4).
• To compare the graphical results with the experimental ones, use the protractor to draw the vectors to scale and compare them with the forces you get in experiment.
[Click on images to enlarge.]
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TA Notes
• Perform the experiment ahead of time!
• Consider both the magnitude and direction whenever comparing two forces.
• Be sure to include the weight of the mass hanger (5 grams each) when you record the mass for each string.
• Whether the forces are in equilibrium can be decided by observing that if the ring is centered on the bolt at the middle of the table i.e. the ring should not touch the bolt. (see Figure 5).
• Make sure no hanger or masses touches the table when they are attached to the strings (see Figure 6).
• Students can work more efficiently in each part of the experiment if they perform the experiment according to the graphical results. To do so, they can first find the correct direction of the desired force, then decide the magnitude of the force by adding the masses to the hangers gradually.
• There are different methods for students to find a set of forces in equilibrium: They can use either the force table or draw the graph to scale. Alternatively, they can use geometry and trigonometry knowledge to calculate them. Make sure they know which methods they are using in their report.
• Make sure you have all the masses for each table after the experiment.

Data, Results and Graphs

Enter TA password to view sample data and results of this experiment:

Lab Manual

The Lab Manual for this experiment does not exist on-line.

CUPOL Experiments

Take a look at these CUPOL experiments for an on-line laboratory experience:

If you have a question or comment, send an e-mail to Lab Coordiantor: Jerry Hester