Force Vector Table

Lab #1 Fors Phys 4A w2010
Force Vector Table
Background: In this experiment you will set up forces on a ring using hanging
weights. Since the force is proportional to the weight, we will measure
the forces in the mass units. You will add the forces graphically and
using trigonometry. You will use this technique throughout all of your
physics classes, so make sure you understand it.
Hypothesis: The vector sum of all the forces on a stationary object is zero.
Equipment: Force table, set of weights, protractor, right triangles
Procedures:
I. Obtain a set of force vectors from your instructor
Graphically determine the resultant force (this means adding the
vectors tail to tip and using a ruler and a protractor)
II. Use trigonometry and vector components to determine the resultant
force vector
III. Set up the force table with the two/three forces and the resultant force
rotated by 180 degrees to determine if the forces balance
Repeat these steps for a second and third set of forces – try four weights if you can
find the materials.
Analysis:
Explain how vectors can be added graphically or by components. Explain how to
calculate the components from measurements of the angles.
List sources of errors such as uncertainty in force, error in measuring angles, etc.
Explain how experimental error will relate to the analysis.
If your angle measurements were off by 1 degree, how much would this change your
trigonometric vector addition?
Conclusion: State your primary findings regarding the hypothesis.
Which technique, graphical addition or using trigonometry, is more
accurate at making these measurements?

Lab #1 Fors Phys 4A w2010
Vector Mass to be placed on holder (kg)
(Don’t forget the mass of the
holder – need to be added)
A
B
C
D
E
F
G
H
L
M
N
P
Vector sum: |A+B|
Angle:
Vector sum:
Angle:
Vector sum:
Angle:
Vector sum:
Angle:
Angle CCW with
respect to x-axis
Graphically Analytically Experimentally