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Hello, my name is Jenna. I am an 8th grade
student at La Colina J.H. I am currently working
on my science fair project. My Science fair
question is:
How does a wetsuit affect drag?
My procedures are:
1.Wear a competition swimsuit.
2. Swim in 25m pool
3. Swim 100m.
4. Measure and document time of 100m swim.
5. Rest 2 minutes.
6. Repeat steps 1-5 nine times.
7. Average the times of all 100m swim sets.
8. After a week of rest, wear a triathlon
swimming wetsuit of 3mm thickness neoprene with
no
arms.
9. Repeat steps 2-7 wearing wetsuit.
My hypothesis is: If the wetsuit does create
drag
then I think the competitive swimsuit will
provide
better speed and time then the wetsuit.
IF you have the time I would really appreciate
answers to these questions.
a. Do my procedures sound like they would
work for
my experiment?
b. Is there anything I could do to make my
experiment better?
c. Would it be better to do five trials of
the
competition suit and then five trials of the
wetsuit on one day then do the same thing a week
later?
d. Is there any vital information about
drag I
should know before conducting my experiment?
e. What is the best way to measure drag?
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Question Date: 2012-11-08 | | Answer 1:
I like your experiment. I like the plan in
(c) better; but I think you should do one day
with competition wet suit first, and the other
day with wet suit first. Then you have a better
control in the experiment, because I'm guessing
you swim faster in the earlier swims? Or, if
you swim faster in the later swims, you have
each wet suit 'doing' later swims. And, if
you're just more energetic on one day than the
other, you'll have swim times in each wet suit
on each day.
Google Scholar is a good place to learn about
things such as how to measure drag.
It's at scholar.google.com
Here's one result, for my search of "wet suit
drag":
The effect of a triathlon wet suit on drag was
studied in 12 subjects (eight male, four female)
swimming at different velocities (1.10, 1.25 and
1.50 m.s-1). The active drag force was directly
measured during front crawl swimming using a
system of underwater push off pads instrumented
with a force transducer (M.A.D. system: 6).
Measurements were made when swimming over the
system with and without a wet suit. A 14%
reduction in drag (from 48.7 to 41.8 Newtons) is
found at a swimming velocity of 1.25 m.s-1,
which is a typical swimming speed for triathlon
distances. At 1.50 m.s-1 a reduction in drag of
12% was observed, which suggests that the
wearing of such a suit might be beneficial in
conventional swimming events. The reduction in
drag can explain the higher swimming velocities
observed in triathletes using a wet suit. The
effect of the reduction is probably largely due
to an increased buoyancy inducing less frontal
resistance. However, since the effect of the
suit on the lighter female swimmers was not
different from the effect on the heavier male
swimmers, a reduction in friction drag and drag
coefficient may also be significant.
This is the article:
Toussaint HM, Bruinink L, Coster R, De Looze M,
Van Rossem B, Van Veenen R, De Groot G
Department of Exercise Physiology and Health,
Faculty of Human Movement Sciences, Vrije
Universiteit, Amsterdam, The Netherlands.
Medicine and Science in Sports and Exercise
[1989, 21(3):325-328]
Keep asking questions!
Best wishes,
| | Answer 2:
Do my procedures sound like they would work
for my experiment?
I'm not sure that you will be able to answer
your original, scientific question of "how". The
procedures sound like they answer the question
of "Which suit provides a better speed swimming
in a pool?" I don't think you will be able to
directly look at the drag, but rather you are
looking at how fast a suit can make you.
Is there anything I could do to make my
experiment better?
I'm not sure what you mean in either of the
suits that you have here - do they have legs to
the knee? to the ankle? sleeves? back cut outs?
So if you have a "regular" competition swim suit
(a one-piece that is similar to what people
would think of as a swim suit), I would then
also look at something that adds to the knee,
and a different one that adds to the ankle, IF
you can borrow one. If not, I think this will
still work, and show the differences.
I would also repeat the whole thing another
time - so once more with the competition suit,
and once more with the triathlon suit.
Also, it's the same person completing all of
these swims right? You don't want to have 2
different people completing these swims.
Would it be better to do five trials of the
competition suit and then five trials of the
wetsuit on one day then do the same thing a week
later?
I think you can cut down on the number of
times you need to time at each trial - but you
don't want to be too worn down when you switch
suits. If you do them all in one day, make sure
to switch which one you use the second time. For
example if the first swims are with a
competition swimsuit on day 1, Day 2 should have
the triathalon wet suit as the first swims. If
you have the time, and conduct your experiment
this way, I'd add a few more days of timing.
Is there any vital information about drag I
should know before conducting my experiment?
What is the best way to measure drag?
See comment in (a)
Also, you can e-mail if you have more
questions/ want to bounce ideas around.
| | Answer 3:
Nice experiment! I have the following
suggestions:
1. Have a partner besides yourself whom you
also do the experiment on, but have your partner
wear the wet suit first (while you're wearing
the swimsuit), and then a week later have her
wear the swimsuit while you're wearing the wet
suit. Also make sure that if either she or you
swim in the week between your measurements, make
sure that the two of you swim together. The
reason is because if you're swimming regularly
in-between trials, then you might be in better
physical shape in the second trial than in the
first, and thus perform better. If, instead, you
don't swim in-between trials, then you might
have lost some of your physical fitness, and
this could affect your results. If you swim with
a partner who is wearing whichever outfit you're
not, and both of you swim better (or worse) the
second week than on the first, then you can
attribute that to being in better/worse shape
than you were in the first trial and not to the
outfit you were wearing while taking the
measurement.
2. You could do five and five for each day,
but also keep in mind that you're going to be
tiring yourself every time you swim on a given
day. This will cause you to not swim as fast,
which you don't want to confuse your results.
3. I'd measure it as how fast you can get to
the other side of the pool.
4. If you're even mildly sick one day, don't
swim. Wait. Postpone your experiment if you have
to. It will hurt your performance, and therefore
screw with your data.
Good luck!
| | Answer 4:
I really like your research question and
experiment. Your experimental design is well set
up and you should get some interesting results.
Keep in mind that there are different forms of
drag. There is friction drag. Friction drag is
the drag that results from the interaction
between the swimmer´s body and the water
molecules and serves to slow down the swimmer.
Then there is pressure drag. Pressure drag
occurs because the swimmer is moving through the
water and there is a difference in the amount of
pressure in front and back of the body. This
difference in pressure causes turbulence around
the swimmers body and can slow down the swimmer.
Among other factors, this kind of drag will be a
function of how the swimmer's body is positioned
in the water. Last of all there will be wave
drag, which occurs when the swimmer or any
object moves through the surface of a
liquid.
So what does this mean for your experiment?
It means that you should observe and think about
how the competivie swimsuit and wetsuit affects
all forms of drag. Obviously the material on the
swimmers body will be different so the skin
friction will be different but does the wet suit
cause the swimmer´s body to position differently
in the water as well? For example, will your
legs be dangling deeper in one of the suits?
Will your body be sticking out into the air more
in one of the two suits? If you can estimate
these variables or at least observe them then
your results will be much more informative in
understanding the effect of the suits on
drag.
Also don´t forget to make observations about
how the competitive suit versus wetsuit affect
other factors than drag. For example, does one
of the two suits affect swimming mechanics in a
different manner? Are you able to move your arms
and legs in the same way in the two experimental
trials? Even if you can´t measure these other
variables you should obverse them and mention
them in your results and discussion. If you have
time you could also test how fast you swim in
just a regular swimsuit.
Feel free to contact me if you have more
questions.
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