Archive for ‘Physics’

May 13, 2015

It’s all over but the ‘caw’-ing

by Janie Jones

I was feeling a bit down, okay I was feeling totally wretched, upon leaving my physics final, and I had a staff meeting at the tour guide gig to attend.  Not feeling one bit in the mood for a pointless staff meeting after a soul crushing physics final, and not enjoying beer, I stopped for a Frosty and some fries and sat in the car overlooking the big lake crying over my salty-chocolatey num-nums and hoping they would work some magic on my mood.

And then what to my wondering eyes should appear?

gull 003

Yup that there is a sea gull.  Or, as it lives off a lake does that make it a lake gull?  I’m not a zoologist.

What ever it is, it landed on the hood of my car and strutted about while I ate, occasionally tapping on the windshield as if it thought it might snatch a french fry from me.  After the shock wore off of being less than 3 feet from the bird (albeit separated by a sheet of tempered glass) I decided to try and get a snapshot.  Isn’t that what people do now-a-days with these smart phones?

Lo and behold my feathered friend sat still and posed quite nicely for me.

It kept me company the whole while I ate, and, as if it noticed and realized I was done and wasn’t gonna get any, it flew off just moments before I put the key in the ignition to leave.

 

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May 6, 2015

Whip it, whip it good

by Janie Jones

Have you ever wondered what it’s like to be a sperm?

No, no.  Stay with me here.  This is no joke.  This is your multidisciplinary science lesson for the week.

So, when you are tiny, microscopic organism, or a single cell such as a sperm cell, your swimming reality is not quite same as what we mega-fauna organisms know as the reality of swimming.  We just jump in the water and wiggle a bit and away we go.  But when you are a tiny microscopic life form, though you swim in the same waters as us big’uns, it’s, well, more complicated.
You see, this is where Janie’s brain explodes, because the dreaded world of physics collides with biology.  As Ricky Ricardo would say, “Janie, you got some ‘splaining to do!”  And, I will try, because it’s way cool.
So, fluids have both viscosity and density.  Straight forward.
There is also such a thing as inertia, right?  You all know about inertia, that an object’s inertia resists changes in its “state,” so the whole an-object-in-motion-tends-to-stay-in-motion-and-an-object-at-rest-tends-to-stay-at-rest-unless-acted-upon-by-something-else (or in the physics world, an external force) bit.
Now imagine you are moving through a fluid.  This means you have velocity.   And it would happen that, in a fluid, the ratio of inertial forces to the forces of viscosity is very important.  If you want to know the physics math it’s:

inertial forces/viscous forces=> density x velocity x dimension (such as length of the body traveling through the fluid)/viscosity

This ratio gives you a value known as a Reynolds number.  The important take away fact is that when Reynolds numbers are very small, as in the microscopic world, the forces of viscosity cancel out pretty much everything else.  In fact, the viscosity squared divided by the density is a force.  And when Reynold’s numbers are very low, this is a tremendous amount of force to be reckoned with.
A paper was written on this subject by E. M. Purcell, June 1976.  So to help put things in perspective, in Purcell’s words, we can get an idea of what it might be like to be a microscopic organism swimming at low Reynold’s numbers if we imagine swimming in a pool of molasses and we can only move at the rate of one centimeter per minute.
In our world, if we dive into the water, or do some sort of stroke, our inertia carries us forward a ways.  But, at low Reynolds number inertia has no bearing.  Microscopic organisms do not experience inertia.  Purcell tells us that if we could give a microscopic organism a push, it would come to a stop in 0.6 microseconds and only travel 0.000000000001 meters.
Pretty wild?  Well, while that might seem hard to imagine, low Reynolds numbers play another key role in how microscopic organisms experience physics and motion.  That is, reciprocal motion gets you nowhere.  Literally.
So, think of floating face down in the water and just using your arms to swim.  You hold your arms out in front of you then thrust your arms to the side.  This causes you to move through the water.  You bring them back forward in the reverse motion and repeat the stroke.  The motion is essentially symmetrical and reciprocal.  Your arms travel the same path each time you stroke; they start and end always in the same place, the movement is reversible.  If you have spent any time in the water you know you’ll be much more effective if you tuck your arms in to your body as you bring them forward, but if you use less force as you bring your arms back in the reverse motion, because of inertia, you will still move forward some.
If you are at low Reynold’s number, however, and you try to repeat the this same kind of reversible, symmetrical motion, you simply retrace your movement forward and backward to the exact same spot due to the lack of inertia.
Weird, but true.
So, every wonder why sperm is shaped the way it is?  Because with out the whip-like flagellum, it couldn’t even compete in the fertilization free-swim.

sperm motion

Google Image search sperm+flagella+whip+motion

The flagellum does not move in a reciprocal or symmetrical motion and does not rely on inertia to help it, instead it beats in a wave-like motion.  As you can see from the image, it does not start and stop in the same place with each whip stroke.  Furthermore, the motion changes the orientation of the whole cell.  And, so it can still propel the cell at very low Reynold’s numbers.
If on the other hand, it’s flagellum flapped like a windshield wiper, or your arm in the above swimming example, the lack of inertia would bring the sperm right back to where it started when it reversed the motion.  Not very effective.  This sperm definitely wouldn’t win the egg hunt.
So if you are having problems with sperm motility perhaps your little swimmers didn’t quite get the proper swim lessons.
Bacteria, on the other hand, have different kinds of flagella which are rigid and can’t “whip” the cell forward.  Instead, many bacteria have a corkscrew shaped flagellum that works like a propeller.  Some have corkscrew shaped “bodies” as well, which rotate to help propel the organism with a propeller like effect.  Other bacteria don’t have flagella at all, but instead have multiple cilia, which are more flexible and can promote “whip” like motion.

Well, I hope that wasn’t too dry or boring.  As much as I hate physics math, I still think it’s fascinating conceptually.  Especially when we see it in our every day lives and how it frames our intuitive functioning within the world around us.  But every now and then if we stop and realize that the world we live in isn’t the same world that is experienced by other lifeforms around us, our intuitive feel for every day physics can be thrown out the window.  That’s when physics can really blow your mind.
So, with beach season just around the corner, next time you go for a paddle, perhaps you might spare a moment to think of the microscopic life teaming invisibly all around you and appreciate how amazing biology is that it can compensate for a wide range of physical realities.

April 27, 2015

Monday Melange

by Janie Jones

Leif had an event to attend in Big City yesterday that was not exactly my cup of tea, besides from the fact it was late in the day and I had homework to do.  But he came in early so we could spend some time together before hand and I dog sat for Vera and Rupert so they wouldn’t have to be left alone at the farm all day.  It was nice to see the dogginses.  We even squeezed in a walk after dinner as it was a lovely, sunny afternoon.  When Leif came back to pick up the dogs on his way back to the farm later that night, I don’t think Rupert wanted to go.  He stood right outside the door until Leif finally called him.  My little guy.  It was very tempting to open the door up and let him back in.

There is just this week and one more in the semester until finals.  I have a poster to present on Wednesday, a physics test on Friday and a microbiology lab test a week from Thursday.  That is all that is left standing between me and finals.  Most people, I think, hate finals.  Me though, I look forward to them.  They symbolize the end of suffering.  Hey, I can take a couple tests and be thrilled to do so if it means the end.

Almost done with physics.  Almost done with physics.  Almost done with physics.

I have been trying to study really hard to for my microbiology final.  I cannot imagine getting a better grade in physics than in microbiology, but I tell you what, I have been very disappointed with the lecture for that class and unless I manage to do amazingly well on the final there is the distinct possibility that the unimaginably unexpected will actually happen.  I’ve also been disappointed with myself, but as much as I *want* to learn this stuff and do well, I am really having a hard time keeping up with the material.  Trying to crack down and commit the material to memory, I spent so much time last Tuesday studying I put my back out.

Seriously.  A reading related injury.

I tend to slouch when I read, especially big, heavy textbooks that are a pain to hold up.  Apparently I sat for so long reading I strained my back muscles.  When I began to hurt from sitting in my “traditional” slouch, I tried to sit and lay in a variety of other poses which I hoped would neutralize the slouch or counter stretch my back.  In the end, I strained a whole mess of back muscles.  Thank goodness for metaxalone and naproxen.

Well my friends, it’s time to get to it.

Happy Monday.

April 23, 2015

Thursday Quote Du Jour: How am I doing in physics? Eh, it’s all relative.

by Janie Jones

The semester, and therefore my foray into the realm of physics, is almost over.  But, we are just beginning to study relativity.

 

When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That’s relativity.

-Albert Einstein
Read more at http://www.brainyquote.com/quotes/topics/topic_funny.html#DVvEbRYbu2vOYWDA.99
April 21, 2015

Tuesday Titters: If Einstein wrote poetry

by Janie Jones

I’ve read in the bowels of Google that Einstein’s favorite limerick was:

There was an old lady called Wright
who could travel much faster than light.
She departed one day
in a relative way
and returned on the previous night.

April 14, 2015

Tuesday Titters: The lights are on but Roy G. Biv is out

by Janie Jones

Where do they send criminal light?

To a prism.

 

March 18, 2015

Some people really just don’t get the concept of Spring Break

by Janie Jones

I can’t friggin believe it.

Physics teacher sent out an email notifying all us lucky students on spring break that he’s posted more homework.

Just when I thought I had cleared my to do list of physics for a few days.

Bastard.