lab exercise 3
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School
Thomas Edison State College *
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Course
115
Subject
Aerospace Engineering
Date
Apr 3, 2024
Type
docx
Pages
5
Uploaded by DeanPheasantPerson1053
Question 1
What is the mass of the system made of the wooden block and the soda can (or the other object that you are using)?
390 G
Question 2
Convert the mass measured in Question 1 to its weight in Newtons. This is the value of F
N
that will be used in the calculations for the tables.
.39 x 9.8 m/s=3.822 N
SURFACES
Wood / Wood (larger surface)
For this case, we will use the larger surface of the wooden block as was shown in Figure 1. Measure F
s
and F
k
as indicated in Section 3.1. Run 5 trials, completing Table 1 below.
Wood/Wood (larger surface block)
Force Static Friction
Force Kinetic Friction
Coefficient. Static Friction
Coefficient Kinetic Friction
Trial 1
2.2
1.5
.576
.392
Trial 2
2.3
1.4
.602
.366
Trial 3
2.2
1.5
.576
.392
Trial 4
2.1
1.4
.549
.366
Trial 5
2.1
1.4
.549
.366
Average
2.18
1.44
.5704
.3764
Standard Deviation
.007
.0042
.000265
.000406
Wood / Wood (smaller surface)
For this section, turn the wooden block on its side as shown in Figure 2 and repeat the experiment, completing Table 2.
Copyright © 2017 by Thomas Edison State University. All rights reserved.
.
Figure 2: Wooden block on its side (courtesy of Chad Saunders, TESU student)
Wood/Wood (smaller surface block)
Force Static Friction
Force Kinetic Friction
Coefficient. Static Friction
Coefficient Kinetic Friction
Trial 1
1.5
1.3
.576
.34
Trial 2
1.3
1.3
.34
.34
Trial 3
1.2
1.1
.314
.288
Trial 4
1.5
1.3
.576
.34
Trial 5
1.4
1.2
.366
.314
Average
1.38
1.24
.4344
.3244
Standard Deviation
.017
.008
.017
.0005408
Wood / Glass
For this section, use the glass surface of your wooden block to repeat the measurements and complete Table 3.
Wood/Glass
Force Static Friction
Force Kinetic Friction
Coefficient. Static Friction
Coefficient Kinetic Friction
Trial 1
.8
.8
.209
.209
Copyright © 2017 by Thomas Edison State University. All rights reserved.
Trial 2
.8
.7
.209
.183
Trial 3
.9
.8
.235
.209
Trial 4
.9
.8
.235
.209
Trial 5
.8
.7
.209
.183
Average
.84
.76
.2194
.1986
Standard Deviation
.003
.003
.0002028
.0002028
Other surfaces
Repeat the measurements using other surfaces (for example, Wood / Sandpaper, Wood / Carpet, Glass / Carpet, etc.) When completing Table 4 below, make sure that you indicate the surfaces you used.
Wood/Countertop
Force Static Friction
Force Kinetic Friction
Coefficient. Static Friction
Coefficient Kinetic Friction
Trial 1
1.1
.7
.288
.183
Trial 2
1.1
.8
.288
.209
Trial 3
1.4
.7
.366
.183
Trial 4
1.1
.7
.288
.183
Trial 5
1.2
.8
.314
.209
Average
1.18
.74
.3088
.1934
Standard Deviation
.017
.003
.00115
.002028
ANALYSIS OF RESULTS
QUESTION 3 Study the results from Table 1 and Table 2. What can you conclude about these results?
Table 2 required less force to initially move and keep the block moving most likely because of the lower
surface area and less friction between the surfaces. Copyright © 2017 by Thomas Edison State University. All rights reserved.
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QUESTION 4
Using the data from the same tables, do you think that the ratio of μ
k
to μ
s
is constant in both cases? If so, what do you think this indicates? The static friction was not constant while the kinetic friction was constant between the 2 tables. QUESTION 5
Studying the standard deviation data from all the 4 tables, which experiment do you think is the most reproducible? Why?
I think that the wood/glass in table 3 is the most reproducible of the 4 tables. The glass surface caused significantly less friction between the two surfaces. This removed some of the variability in the amount of friction being produced. This amount of friction was not always a constant factor and using the glass removed most of that variability.
QUESTION 6
In general, how does the coefficient of static friction compare to the coefficient of dynamic friction?
In all cases the coefficient of static friction was larger than the coefficient of dynamic friction.
QUESTION 7
In designing machinery, would we prefer to use materials with larger or smaller coefficient of friction? Explain your reasoning.
You would want a smaller coefficient of friction simply because the larger the coefficient the harder the machinery needs to work while the smaller the value the easier it is for the machinery to do its job with less force. QUESTION 8
In driving a vehicle, would you prefer to use materials for the contact between the wheels and the road with larger or smaller coefficient of friction? Explain your reasoning. In this case you want to find materials that have a good balance between the two. Too much of a coefficient and the vehicle will have to work harder to move while not having enough would cause the vehicle to not have enough traction and potentially be uncontrollable. Copyright © 2017 by Thomas Edison State University. All rights reserved.
The purpose of this experiment is to show how different material surfaces have different amounts of friction which then require different amounts of force to bring those objects into motion. Additionally, this experiment showed that once an object is in motion it requires less force to keep
it in motion than it did to get it into motion. I used the same board that I used for lab #2 to conduct
this experiment and I used my kitchen countertop for the last table. I originally tried to use the sandpaper on the board for my 4th experiment but it did not provide a smooth motion because it was jerky and hard to establish how much force was required. Instead I switched to the wood on my countertop to provide a smoother surface for the block to slide and measure. Another area of concern that I had in this experiment was that I was really trying to focus on applying the same amount of force on the block throughout the experiment.
Copyright © 2017 by Thomas Edison State University. All rights reserved.