Spring Constant Report Template

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Carleton University *

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1007

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Physics

Date

Dec 6, 2023

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docx

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Carleton University Laboratory Report Course #: 1007 Experiment #: 2 Spring constant Ali Khelil (101258560) Date Performed: Oct 16, 2023 Date Submitted: Oct 30, 2023 Lab Period: L1 Partner: Goodness Station #: 16 TA: Teresa
Purpose The purpose of this experiment was to determine the spring constant of a hanging spring using two different methods. The first method that we attempted was the static method to figure out the spring constant. In the experiment we had used a motion detector, the spring, and a force sensor. The second method of determining the spring constant is by using the dynamic method. The static method was determined by suspending masses of different weights and then measuring how much the spring extended from rest, using a motion sensor to determine the extension. The dynamic method was determined by allowing the spring to oscillate with different masses on it. The spring constant is represented as k which informs us that the force on a spring is directly proportional to the extension of the spring so long as the spring does not become deformed when it reaches its maximum extension. For the dynamic part of the experiment, simple harmonic motion was used. For the static portion of the experiment, Hooke’s Law was used. Observations/Graphs Use templates from previous labs to copy/paste any Figure and Table numbers for your captions. Static Method: Figure 1: A graph of the spring constant using the static method. A linear fit was done for this data set to show how the extension of the spring compared to the force in newtons are linear. Table 2: the slope and the Y-intercept collected from the experiment using logger pro. The slope and Y-intercept uncertainties were calculated in logger pro. Unites are shown below the values. Slope Y-intercept m σ m b σ b Value 20.47 0.2061 0.04798 0.03060
Units N/m N Dynamic Method: Figure 2: A graph of the spring constant using the Dynamic method. A linear fit was done for this data set which compared how the Mass attached to the spring effects how much the spring oscillates. Table 2: the slope and the Y-intercept collected from the experiment using logger pro. The slope and Y-intercept uncertainties were calculated in logger pro. Unites are shown below the values. Slope Y-intercept m σ m b σ b Value 0.05002 0 0.004756 0 Units S 2 /rad 2 /kg S 2 /rad 2 Calculations Part One: Static Method: Sample calculations of the mass of the weight on the spring being converted from g to kg, the spring extension being converted from cm to m, and determining the force of gravity (f g ). 50 1 kg 1000 g = 0.050 kg 10.5 cm 1 m 100 cm = 0.105 m
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F = M ×g = 0.050 kg× 9.8 m s 2 = 0.490 N If the spring extension is equal to the slope of the graph, then the uncertainty for k s and σ s is equal to the uncertainty of the slope. therefore, the spring constant can be written as: k ( ¿¿ s±σ s ) N s 2 ¿ ¿ ( 20.47 ± 0.2061 ) N s 2 determining the acceleration due to gravity on the Planet: F = kx F = Mg therefore kx = Mg g = kx M g = ( 20.47 )( 12.5 ) 50 g = 5.118 m / s 2 Calculating the t-test to compare the expected y-intercept: ¿ x 1 x 2 ¿ σ 2 + σ 2 t = ¿ ¿ 0.04798 0 ¿ 0.0306 2 + 0 t = ¿ t = 1.568 Since the value for t is less than 2, this shows that the results are consistent. Part Two: Dynamic Method Calculating the spring constant:
m = 4 π 2 k k = 4 π 2 m k = 4 π 2 0.05002 s 2 / rad 2 / kg k = 789.25 kg s 2 Converting the Kd units to the SI units: N m = kg m s 2 = kg s 2 Calculating the uncertainty: σ 1 ω 2 = 2 σ ω av ω av 3 σ 1 ω 2 = 2 ( 5.363 ) 5.363 3 σ 1 ω 2 = 10.726 154.249 σ 1 ω 2 = 0.0695 Calculating the t-test to compare the two values ( 𝑘? ± 𝜎𝑘? ) and ( 𝑘? ± 𝜎𝑘? ): ¿ x 1 x 2 ¿ σ 2 + σ 2 t = ¿ ¿ 789.25 0.04798 ¿ 0.0695 2 + 0.0306 2 t = ¿
t = 789.202 0.0759 t = 10392.688 Discussion The spring constant that was found for the static method is 5.118 m/s 2 and for the dynamic method it was 789.25 N/m ± 0.0695. the reason for such a high spring constant for the dynamic method could be due to a low m value on logger pro or simply due to bad calculations. Personally, I find the static method more reliable, and I feel this way for two reasons, the first being that it is simply less tedious. The second reason is that a source of error in the dynamic method lies with the timing aspect. I may not have started and stopped the timer exactly at the beginning and end of the oscillation period. This could vary from person to person, and trial to trial. As such, I believe that the static method yields more consistent results. While in the simulation it is relatively easy to measure the extension of the spring for the static method, in real life, however, there is damping, and it is quite a bit harder to measure the spring extension as there is no readily marked equilibrium line. As such, the experiment might need to be repeated a few times to ensure reliable results. For the dynamic method, as there is no marker per oscillation period, the mass would be pulled down and the spring would be allowed to perform a few periods. The time would then be divided by the number of oscillations performed to determine the period. While a series combination of springs entails that two springs are connected, with a mass hanging from the bottom, a parallel combination of springs consists of two springs, side-by-side, with a single mass suspended from both. The spring constant is dependent on force and mass, and as such the extension would be multiplied by two for a series combination but divided by two for a parallel extension. Therefore, the individual spring constant values per spring would be added for a parallel combination, and the inverse of each individual spring constant values per spring would be added for a series combination. As such, the parallel combination system would yield a larger total spring constant. Knowing the spring constant of a spring is useful in that it allows the individual to know how much force is required to stretch the spring, and therefore how stiff the spring is.
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