Forces at Equilibrium
Asma kayen
ID# 201001948
Group members:
Asma Kayen
Maram AlDukhayyil
Section: 211
Submission date: 03-10-2012
PHYS 1411: Introductory Physics Lab
Lab Instructor: Nouf Al-Jalaud
Prince Mohammad Bin Fahd University
Fall 2012-2013
1. Abstract (Objective)
The experiment was about forces equilibrium. The objective of the experiment was to
study the object under a static equilibrium and test the results mathematically.
2. Theory
The mathematical formulas used in calculations were based on newatons second law
which states the sum of all the forces:
1- M3 =(M1sinθ1+ M2sinθ1)
 M1sinθ1 = the first force multiplied by the Sin of its angel.
 M2sinθ1 = the second force multiplied by the Sin of its angel.
 M3 = fixed force.
2- Average Value: Sum of all trials\number of trials
3- Percentage Error: (|Approximate Value-Exact Value| / |Exact Value|) x
100%.
Approximate value is the Average Value and Exact Value is the M3.
3. Method
On a force table assembly we hanged on a fixed angle 270° M3 mass the adding on
M1 and M2 masses then we adjust the angles of the M1 and M2 till we reached the
equilibrium. It reaches the equilibrium point when the knot of the three threads that
are joint all together over the hole in the middle of the forces table. We took the
readings of the angles of θ1 and θ2 then we calculated the M3 = (M1sinθ1+
M2sinθ1) then we write down the result and do the same thing 3 times with different
masses to get a better result.
4. Data
Trials
1
2
3
M1
30
20
40
θ1
45
38
352
sinθ1
.70
.61
-.10
M3= 25 = at 270°
M1sinθ1 M2
θ2
21.2
20
166
12.31
20
144
-4.18
50
143
sinθ2
.24
.58
.60
M2sinθ1
4.83
11.75
30.0
M3
26
24
25.9
5. Data Analysis (Results Discussion)
After each trail we used the M3 formula to get the final answer for each trial.
We recorded the masses of M1 and M2 then we find the Sin of each angle and
multiplied it by its mass we do the same thing for the 3 trails. After that the sum of
M1sinθ1 and M2sinθ1 should be equal or close to the mass of the fixed force M3.
Next we found the Average value which is the sum of the final results in all of the
three trials and divide them by 3. Finally we used we used this formula
(|Approximate Value-Exact Value) \ |Exact Value|) x 100 to find the percentage
error and it was 1.2%.
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6. Conclusion
In conclusion, the experiment requires accrete numbers and angles to get an efficient
result. Static equilibrium refers to an object that is not moving the sum of all the
forces acting on an object in static equilibrium must add to zero F = 0. It’s also
about how to balance to reach the equilibrium
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