Lab 1: Addition of Vector Forces
Purpose:
In this experiment, we measured 3 different forces: two forces were made by the
spring scales, and a third force of gravity on a mass. Once we had measured these forces,
we added the vectors using tail to tip method. The purpose of this lab was to practice
vector addition using tail to tip method and to see if an object wasn’t moving, then the a
vector sum of the forces was zero.
Theory:
A vector is a measurement that has both a magnitude and a direction. Because
vectors have a direction, they must be added using either tail to tip method or
algebraically with Pythagorean theorem.
In this lab, we had three vectors: the two forces measured using the spring scales
and the force of gravity on the mass. We added the two spring scale forces together and
found that they were almost identically equal in size and opposite in direction to vector C.
This is expected because the mass wasn’t moving, which implies that the net force must
be zero.
Materials:
 2 Ring Stands
 1 Crossbar
 Masking Tape
 String
 Protractor
 Scissors
 Level
 2 Spring Scales
 500g Mass
 Notebooks (for leveling)
*** Remember to include a sketch after you print!***
Procedure:
1) When we started to assemble the apparatus we taped a bar across two of the ring
stands.
2) We then put two spring scales and tied string to the end of each spring.
3) Then we put a 500g weight on the middle of the string to measure the amount of force
acted on the weight to hold it up.
4) We had to level out the right stand because it was smaller than the left so the angle
would be off if we did not fix it.
Results and Data:
𝐴⃑ = 2.8𝑁, 𝐸75°𝑁
⃑⃑ = 2.4𝑁, 𝑊80. °𝑁
𝐵
𝐶⃑ = 4.9𝑁, 𝑆
Analysis:
1. I used 1N=2cm for my scale.
2. Vector for A + B has almost the same magnitude and the opposite direction as
vector C.
3. See attached paper.
4. My answer is close to zero but not exact because with every experiment there is a
little bit of error. But in a perfect world my answer would have been zero.
5. I would expect if I added B to C I would get -A.
6. I would expect if I added C to A I would get -B.
7. The order in which you add vectors doesn't change the answers so therefore my
answer would remain the same.
Error Analysis
Some errors that occurred that changed the results of the experiment are that the
crossbar was not perfectly level, because the level we were using was not calibrated
properly. This was an unavoidable error. The surface the ring stands were set on moved
slightly when it was bumped, and may have altered the scales readings slightly. This error
could have been avoided by simply not bumping the table.
Another unavoidable error that we had to deal with during this experiment was
measuring the angles. The protractor was large and the spring scales were thick so it was
difficult to narrow it down to one degree that we called our angle. The protractor was also
held in our hands and not set up so it was a little wobbly and may not have been a perfect
90 degrees that we were measuring from, and as we measured we were adjusting it so it
may have been a slightly different result if it was set up so the protractor wouldn't move.
Conclusion:
The main point of this experiment was to identify each of the three forces and
how they acted. The force pulling down was 4.9N and each of the springs were pulling up
at 2.6N and 2.8N and when we did it using tail to tip method we came up with 5N which
is almost the exact same as 4.9N but it was the opposite direction. We expected this result
because we knew that the mass wasn’t moving, meaning net force must be zero.
Calculations and Data: See attached pages.