LAB 2
Addition of Vector Forces
When two or more forces act at the same time on an object and their vector sum is zero, the object is in equilibrium. Each of the arrangements shown in Figure A illustrates three concurrent forces acting on point P. Because point P is not moving, the three forces produce no net force on point P, and the systems are in equilibrium. In this experiment, you will determine the vector sum of two of the concurrent forces, called the resultant, and investigate the relationship of the resultant to the third force.
Objectives
Observe the interaction of concurrent forces. Apply vector addition to obtain the forces in equilibrium.
Materials: 1 force table
2 hanging mass holders
1 set of hanging masses
1 set of disk masses
Diagram
Procedure
1. Set up the force the pulleys set at various angles.
2. Attach a known mass to one of the lines along the pulley.
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3. Hang disk masses on the mass holders along the other pulleys until the ring in the middle does not slide towards any one direction. Record the angle and the total mass for each direction. Don't forget to include the mass of the mass holder.
4. Repeat for two more trials using different angles.
Data and Observations
Show your data in a data table for all three trials.
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Trial # |
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1 |
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2 |
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3 |
Sample calculations:
Resolve each vector into components for one trial. Name them as vectors A, B, and C. Show a diagram for each vector and put results in a table.
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Trial # |
Ax |
Ay |
Bx |
By |
Cx |
Cy |
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1 |
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2 |
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3 |
Calculate the magnitude and direction angle of the resultant force of A + B .
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Trial # |
Magnitude of A+B |
direction of A+B |
Magnitude of C |
direction of C |
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1 |
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2 |
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3 |
Find the % difference between the magnitudes of the resultant of force A+B, relative to force C. (magnitude of A+B minus magnitude of C) / magnitude of C
Find the vector sum of the three vectors and its magnitude and the per cent of the magnitude relative to the average of the three vectors for all three trials.
Display the components of each vector, the sum of A and B, the per cent difference for the sum relative to C, and the vector sum A + B + C and the per cent magnitude for all three trials in a results table.
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Trial # |
Magnitude of A+B |
Magnitude of C |
% difference |
Magnitude of A+B+C |
% magnitude |
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1 |
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2 |
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3 |
Analysis and Conclusions
3. Explain the results of the per cent magnitude of vector sum of A + B + C.
4. Suppose that you had added B to C. What result would you expect?
5. What result would you expect if you added C to A?