Force Table: Addition of Vectors

• Pre-Lab Checklist
• Experiment Notes: Things to keep in mind while performingthe experiment.
• Analysis Notes: Questions to answer while analysing theexperiment.
• Grading Breakdown
• Return to Physics Lab home page.

Pre-Lab Checklist

1. In your own words, describe the situation to be studied.

2. List and define all the parameters which will be measured directly.

3. List any quantities that will be calculated.

4. List any diagrams that will be created during the analysis of thisexperiment.

Experiment Notes

1. In this experiment you will be using three different methods to addsystems of force vectors.

1. Physical Method: Sets of tension forces will be applied to a ringwhich is centered on the force table. When the ring is in equilibrium, thetotal force on the ring is equal to zero.
2. Graphical Method: The force vectors are represented by arrows drawnto scale at the appropriate angles. (One possible scale is 1.0 cm = 0.25 N) Thelength of the vector represents the size of the force.
3. Algebraic Method: The vectors need to be resolved into theircomponents in the x and y directions. The resultant vector'sx component will then equal the sum of the individual xcomponents. Likewise for the y components. Since the x andy components are at right angles to one another, the Pythagorean Theorumcan be used to find the total length of the resultant vector.

2. In steps 1-5 of the procedure, you will be asked to use the Physical Methodfirst and then to use the known physical result to check your work using theGraphical and Algebraic methods.

3. In steps 6-7 of the prodecure, you will be asked to use the Graphical andAlgebraic methods first to predict the resultant for a set of three vectors. The Physical Method will then be used to check your prediction.

4. In steps 8-9, the "live-action" force table will be used by two lab groupsworking together to find the components for force of known magnitude at aparticular angle. Every group in the lab section will use the same magnitude,but each group will need to find its components at a different angle.

Analysis Notes

1. Your results section should include the resultant magnitude and directionfor all three methods for each of the three parts of the experiment. Pleasesummarize your results into a table. You should also include the componentsyou found for your assigned angle at the "live action" force table.

2. Show ALL of your work. If your first attempts at the graphical oralgebraic method does not match the physical method, check your work, and then show both the orignial attempt and the corrected work with your explaination ofthe corrections you made.

3. When comparing the three vector addition methods, answer the followingquestions about the experimental errors involved in each of the three methods.

1. How similar are the values you obtained using these three methods? Did anyone method give you a result markedly different from the other two? If so,explain why you think this happened.
2. The experimental error in the physical method was affected by which twofactors? What are the ratios of the errors to the measurements of magnitudeand direction (error in force divided by force and error in angle divided byangle) for your resultant vector using the physical method?
3. What factors affect the experimental error in the graphical method?factors? What are the ratios of the errors to the measurements of themagnitude and direction for your resultant vector using the graphical method?
4. What factors affect the errors inherent in the algebraic method?

4. Did your measured values for the force components in Procedure 8 matchthe predicted values calculated using sine and cosine of your angle? What isthe percent error between the predicted values and the actual values? To whatto you ascribe this error?

Grading Breakdown