Posts Tagged ‘Water’

Resonance Frequency… of Walking!

Fish tank, Stationary

This summer I had the distinct privilege of participating in an internship for the Society of Physics Students and the American Institute of Physics. I’m working with the American Physical Society (APS) in their Outreach department, on a (VERY VERY COOL) project called “PhysicsQuest“.

I’ll expand on PhysicsQuest and why it’s so awesomely cool in a separate post (which it deserves). For now, I want to discuss a rather amusing incident that happened the other day at the office.

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Olympic Controversy: How does the “Space-Age Swimsuit” Work?

The Olympics Games are here (well, in Beijing) and everyone’s watching and trying to guess who will win a medal. But, apparently, even the Olympics is a source of scientific inquiry, and not just for geeks. The “Speedo” controversy raises some interesting points about the effect of a swimsuit on the swimmer, and the effect of physics in general as a consideration for the athletes. As we all know, specifically if you’ve been reading the other posts on this site, physics is everywhere, and it’s time we start making sense of it.

Many sites out there reiterate the controversy, but few actually explain what and why it is. In other words: What, really, is the effect of a swimsuit on a swimmer? Why would it give an “unfair advantage”? Can a “Space-Age” swimsuit help Michael Phelps reach his 8-medal dream?

Speedo LZR Racer Swimsuit Official Webpage

Speedo LZR Racer Swimsuit Official Webpage

Since this subject raises some controversy and doubt, I decided I should check it out. I went to Speedo’s official website and read through all their specifications for the Speedo LZR RACER swimsuit (the source of the controversy, and the one Michael Phelps is wearing) and examined each feature.

But First: Physics in a Nutshell

When looking at moving objects (like balls, or planes, or rockets, or swimmers), there are forces at work. The swimmer exerts force forward and spends energy “fighting” whatever other forces that might be applied in the opposite way.

In physics, in order to predict the speed or acceleration of a certain object, we can draw a rough schematic of the known forces that apply on the object. The sum of all the forces (forward, backward, up, down, diagonal, etc) is the final force.

For more on what a Force is, click here.

About Friction and Drag

In general, every moving object (unless it is in a vacuum, which is very hard to achieve) is affected by friction. The amount of friction depends on the material that the movement is performed on. Ice has a relatively low friction, while cement has a relatively high friction.

Drag is very similar to friction; it is a mechanical force (see above figure) that is exerted on a solid object moving through liquid. The interaction between the moving object and the liquid that it moves through creates a “backwards” force that slows that object down. That force is drag.

Drag depends on the shape of the object and its aerodynamic form. Bulky objects will “suffer” more drag and will be slowed down quicker. Slick objects will have less drag.

That’s why the dog (furry and bulky) can’t swim as fast as the shark (slick and aerodynamic). Poor, poor dog.

The Speedo LZR RACER’s Features, Explained

LZR Pulse:

The official website claims that the suit is made of “ultra lightweight, powerful and water-repellent” material, and that it reduces “muscle oscillation and skin vibration”, which in turn leads to “low skin friction drag”.

The LZR Pulse swimsuit claims to shape the swimmer’s body, forcing his (or her) muscles and skin into a bullet-shape aerodynamic structure that reduces the drag – and allows the swimmer to move faster while expending less energy.

The water-repellent feature of the swimsuit essentially causes it to have less interaction with the water. Since drag is caused by the interaction of the swimmer and the water, this feature will reduce the drag (and friction) even more.

Finally, as you could see in the video (embedded at the end of this post, produced by Speedo), the swimmers’ muscles oscillate — move back and forth quickly — while water is flowing at them.

This muscle-oscillation causes the muscles to change shape, which causes the aurodynamic property of the swimmer’s body to change also. In order to maintain the ideal aerodynamic shape, the swimsuit holds the muscles tightly and produces a slick, stable surface that reduces surface tension, increases the velocity of the water flow next to the body, and eases the movement of the swimmer.

LZR Panels

Speedo’s official website claims that the swimsuit has “ultra thin, ultra powerful, ultra low drag” panels that are embedded “at strategic points on the swimmer’s body”, which are meant to “deliver optimum streamlined shape and drag reduction”.

The Shape is one of the most important factors in drag reduction and the creation of an aerodynamic structure. As we said before, bulky objects are subjected to more drag (and more friction), and streamlined objects (like the shark) are subjected to less drag.

The main reason for this is the flows that are created from the movement of the object inside the liquid. Something very similar happens within winds (in case of a plane) or water (in case of Michael Phelps). The liquid flows either slow the swimmer down or make him (or her!) move more easily.

Aerodymanic flows on an airplane wing. Source: http://www.classicairshows.com/

Aerodymanic flows on an airplane wing. Source: http://www.classicairshows.com/

The above depends on the shape, and that’s what the suit claims to produce: A better aerodynamic shape for the swimmer’s body, depending on key areas that might usually produce more of a problem for such structure.

Core Stabilizer

The “internal Core Stabilizer” is, according to Speedo, like a corset; it “helps [the swimmers] maintain the best body position in the water for longer”.

The human body is not exactly aerodynamic in nature, and part of a swimmer’s training is to learn how to hold himself in the water so his body takes the best aerodynamic shape possible. Maintaining this position – specifically in the water – also takes energy from the swimmer. If, indeed, the swimsuit “holds the swimmer in a corset-like grip”, it can assist him (or her) in the effort to hold their bodies in the proper position, and help them spend that energy on gaining speed instead.

Bonded Seams

The LZR Racer claims to be the “first fully bonded swimsuit.” The problem with seams, usually, is that they have stitches. Stitches are adding mass and weight to the fabric (not only the string itself, but also the fact that stitches require folding the fabric, hence increasing the amount of fabric in that location), and they are also bulkier. Eliminating the stitches will make the suit lighter and without unnecessary ‘bulks’, thereby improving the aerodynamics.

Speedo claims that the LZR Racer has “Ultrasonic welded” seams. The seams are not ‘sewn’ but welded, which means that no string is used, and no folds are needed. Ultrasonic welding is a technique that uses high-frequency vibrations on a material under pressure to seamlessly bond two pieces together. The main feature of such technique is that no soldering material or any sort of glue is needed – hence no extra weight, folds or bulks are produced and the suit remains seamless and homogenous.

Ultra Low Profile Zip

This is nothing new; the zipper is “bonded into the suit”, which is common in all swimming suits to make sure that the bulky shape of a zipper doesn’t stand out of the overall shape of the swimmer’s body, and interrupts the water flows.

Unique 3D Three Piece Pattern

The claim on this feature is that the suit is “Dynamically engineered to optimise the shape of the swimmer” (all ye Americans – they mean ‘optimize’). This seems to be mostly a sales pitch; it’s not much different that their “Unique Core Stabiliser” (again, the British spelling).

Summary

Additional Side Note: In order to claim that the suit makes the records rather than the swimmer, or that there is a truly ‘unfair advantage’ for the swimmers who wear this suit, it’s not enough to just see the claims Speedo is making. What needs to be done is have Michael Phelps try out his world-record-breaking with this suit, and with a different suit; if there is an overwhelming difference in the results, perhaps there’s a cause for complaint from other swimmers. Seeing, however, the amount of records (and the overall achievements) in Michael Phelps’ athletic history, claiming that it’s the suit that makes the record might be doing some serious injustice to this obviously-talented swimmer.

All in all, the Speedo RZR Racer swimsuit looks absolutely beautiful, and its claims do fit with reality and physics. As to whether or not it is giving the swimmer an “unfair advantage”, I can’t judge, since I haven’t compared it to any other – perhaps similar – swimsuit in the market.

What I can say quite confidently, however, is that regardless of its features, the person wearing the suit needs to know what he (or she!) is doing. In other words, I could wear this suit ’till my face turns blue (which will probably happen pretty fast, judging from the ‘corset-like grip’) and I’d still never have gotten anywhere close to Michael Phelps’ (or any of the other Olympic swimmers) speed.

That said, I can also summarize this analysis by concluding quite confidently that this suit is, most definitely, better than the one originally worn by Olympic swimmers. They, by the way, used to swim nude.

YouTube Promotional Video

[youtube:http://www.youtube.com/watch?v=dvMdqvO3R9g]

Extra Resources:

Spare Change in Potential: How to Make a Battery From Coins

coinbattery

I don’t know what about you, but I have a box I keep my change in. I’ve bene thinking for a while what I can do with that change – buy a boat, rent a jetski, get a trip on those cool X-Planes that go up to space, etc etc. Big plans for small money, I know, but.. I’ll keep on dreaming.

Now, though, you too have something to do with your extra nickels and pennies you keep safe for future plans: You can do science with them! Yay!

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Bending Water with a Plastic Comb

electrocomb

Yes, yes, I seem to have an affinity towards bending stuff, specifically wet stuff. Last time I bent a laser beam using water, and this time I’m going to magically bend water using a plastic comb.

Science magic! Okay, well, it’s not quite magic, it’s science magic, which means it has (as always) a perfectly good explanation to it. But – can you guess it?

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A Physics Party Trick that Sucks… Liquid

suckliquid-experimentvid

Well, this is going to be sweet, short and to the point: Fire in closed spaces can really suck.

Ha, I was dying to use that pun for a while now, and here I had the chance. This experiment is a really short and sweet one, and can join your mental arsenal of “party tricks” for the partying geeks. It can really impress anyone, and from now on – you are going to know what makes this happen.

Ready?

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We’re SmarterThanThat

The scientific method is all around you, and you use it without even noticing. Science can be fun, interesting and engaging; you don't have to be a nerd to enjoy understanding the world around you. Read More...

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