16 posts tagged “physics”
I'm pretty close to being able to get into the Astronomy class that I want in the Fall semester - at a different college. Maybe I've mentioned before the oddity that UCF offers Intro to Astronomy (AST 2002, at least at UCF) but they don't offer the lab... ever... or at least not anytime in the past or next couple of years. But the lab is kinda sorta required for my Astronomy minor - I could get around this requirement by taking the Physics II lab, of course, but that, you see, would mean that I was taking Physics II. (Do. Not. Want.) Yes, I understand that my whining permits were all revoked when I got that B in Physics I, but it was extremely painful and required a huge amount of help from my beloved, and is an experience that I do not wish to repeat, much less amplify.
So, I am attempting to take Intro and the lab at the other local community college (Seminole Community College) because they are the only place that offers the lab. They also have a cute little planetarium where they do shows on the weekend and for student field trips. Anyway, my transient student form has been approved by the hundred or so (by which I mean three) people through whom it had to pass by at UCF. Now I am waiting on a single approval from the registrar at SCC. Come on dude, or dudette... don't leave me hanging!
And I got a "B" in Physics! I'm so happy!! Woot!!! (And many thanks to my beloved for homework, quiz, and study help.)
So, my adventures in math and science aren't over yet, but the first installment is finally coming to an end. The spring semester is over and my physics final is Tuesday. Whew! And, after all of the pain and whining and hair pulling, how will it turn out?
Well, as it turns out, I'm not actually doing nearly as poorly as I thought. Yes, my test scores were pretty abysmal, but fortunately my homework, labs, and our multiplicity of quizzes were quite high, so I'm actually at a pretty comfortable "B" right now. I can't even express how happy that makes me. As an English major, this higher math stuff really makes me feel dumb, so even a "B" feels like a real accomplishment for me. My hope is that I can solidly nail the final and actually get an "A," just for the hell of it, but it seems that I have a pretty high test anxiety for physics, so the likelihood is... slim. But a "B" is damn fine, as far as I'm concerned!
Next I'll be moving on to my astronomy classes, which I'm looking forward to. If I survived physics, I know that I can make it through the rest! Though, as a counterpoint, my ego would like to mention that I actually got a 100% "A" in my senior level Technical Documentation III class. Go me... I'm not a Physics major for a reason, you see...
Waaaaayyy back in January I wrote a physics post - of the depressingly few physics posts I managed to create this semester - about velocity and acceleration. Well, now I'm cramming for the final exams and going back over the old material in hopes of... well, more about that in a second...
So, in January, I said: 'The first thing that threw me was to learn that "acceleration" doesn't really mean "speeding up." In Physics, it just means "changing velocity."' Today I finally got a slightly better understanding of the concept thanks to a handy little book that I wished I'd picked up three months ago: Physics the Easy Way by Robert L. Lehrman. (Ummm... yes, it is in fact a Barron's study guide.)
Okay... acceleration is still not just "speeding up" but it is a little bit more than simply "changing velocity." Acceleration is the rate of change of velocity. In other words, it is a number, or rather a vector, than describes what velocity is doing. Sadly, this should have made sense a long time ago, as I did understand that acceleration is the first derivative of velocity, and "rate of change" is one of many ways to describe a derivative. Duh... I also had a really tough time with understanding the direction that an acceleration vector took - for instance, why it wasn't always or even often in the same direction as velocity - apparently I was still hanging on to the idea of acceleration really meaning "speeding up," even though technically I knew better.
So, now I see that the acceleration vector always points in the direction of the change in velocity, not necessarily the actual direction of velocity. Therefore, when an object is speeding up and its velocity and acceleration have the same sign (both positive or both negative) then the acceleration vector points in the same direction as the velocity vector. Conversely, when an object is slowing down and its velocity and acceleration have opposite signs, then the acceleration vector points in the opposite direction of the velocity vector. And finally, if an object changes direction but does not change speed, then the acceleration vector darts off on a tangent perpendicular to the velocity vector, and that tangent is "toward the side to which the object is turning."
And that turning while not changing velocity thing? That's what causes what we commonly call "centripetal force" or centripetal acceleration. If you take a bucket of water and spin around with it the water doesn't spill out because of the centripetal acceleration. The velocity vector keeps trying to go out straight, away from your body, but you keep changing the direction. Every time the velocity vector changes direction, the acceleration vector heads perpendicularly back in toward your body...the acceleration force is moving inward, and not out and away from you.
At any rate, more about Physics the Easy Way later... I'll probably do a book review when I've had some more time to look at it. It is definitely "physics light." It doesn't go very deep but so far I'm finding it a good place to get a dumbed down explanation when my class text befuddles my brain. In other words, it can in no way replace a real physics book, but it seems to be a decent supplement.
We are well recovered from the hospital incident now, but have been struggling to get back on top of the work and school that we missed while we were otherwise occupied. We also took a lovely weekend of our spring break from community college (UCF spring break was... well, actually, was the week I was in the hospital... fun!) to go to St. Augustine to visit with my Dad and stepmom, but also to chill and get romantical. We had a very, very good time.
Soooo.... the good news is that I may not have to repeat Physics over the summer after all. We finally got back test number two, on which I got a "D" (as expected), but The Best News Ever is that I actually managed a "B" on test number three. Cosmic balance, or something like that. This was largely due to a lovely bit of unexpected extra credit, but I actually successfully completed the problem that gave the extra credit - even though it was the type of problem that generally frustrates me to no end and makes me quit halfway through. So, now I must just survive one more test and a multiple choice final exam, which is to be drawn from a pool of the quiz questions we have been doing all of this time. Additionally I have not quite a week between my last UCF final exam and the Physics final to prepare. I just have to manage a "C" overall for it to count for my minor...whew!
Next I just have to find out if I will be allowed to take Astronomy and the lab at yet another community college instead of UCF. One of the frustrations of UCF, or at least the Astronomy minor at UCF, is that apparently no one is interested in teaching the lab part of AST 2002, even though it is one of the required choices for the minor. The other choice is to take the Physics II lab - and therefore Physics II. Not my first choice, naturally. Besides, I really want to take the Astronomy lab. At any rate, if I can, I'll take AST 2002 plus lab at Seminole Community College and have it transfer to UCF so that I can continue with the rest of the Astronomy minor. I hope.
Final note, tickets for another shuttle launch are going on sale soon... Monday, I believe. We are going to try to get tickets again, and this time it will be a daylight launch. It is very hard to get tickets for daytime launches though. They tend to sell out within a matter of seconds, probably because some scalper is buying up large blocks of tickets. We have yet to be fast enough over either internet or phone to score daytime launch tickets. Night launches are apparently much easier to acquire, probably because few people are mad enough to hang around until 3 or 4 am and then drive home in heavy traffic while exhausted. Wimps.
Since I'm linking like crazy, generally due to lack of time, and since I've already brought up Cocktail Physics, generally due to my crush on Jennifer Ouellette, minorScience now brings you:
The actual book can be found here:
Note that this is not an early Sunday Brunch and I have not (as of yet) read this book, so I don't know how it is, but I think that the idea is very good, at least. A stolen quote from the above linked interview is thus:
Q: Who is your target audience?
DLP: My book is meant for the NASCAR fan who doesn't know a lot of science, or the science fan who doesn't know a lot about NASCAR. The writer Margaret Wertheim pointed out that people who are already interested in science are very well served. It's the people who don't know that they're interested in science that we fail. NASCAR has 75 million fans. If this book gets even a very small percentage of them to think about taking a science course, or ask their teacher about springs, I will be thrilled. My goal is to stimulate people's interest.
In the event that I actually live through this semester of Physics and am ever able to read any book other than The Fundamentals of Physics I believe that I would give this one a try.
The idea for Talk Like a Physicist day comes from science writer Jennifer Ouellette of Cocktail Physics (whom I want to be when I grow up). I learned about the holiday just today from another fine Physics site which I enjoy but rarely understand, Cosmic Variance.
Speaking of lack of understanding, I am relatively certain that I failed a Physics exam this morning. Go me! This does not bode well for my goal of growing up to be just like Jen...
I love words. It's one of the main reasons I'm a writer. I love finding out what words mean, how they are pronounced, and where they came from, their history - how they used to be pronounced or spelled and how their meaning has changed over time. Would you believe that there is an entire class of words in which the same word has two very different and nearly opposite meanings? They are called autoantonyms or contranyms, among other things.
Autoantonyms are more common than you would think; I found a list of 50 pretty common ones recently. This happens for a number of reasons. English, for instance, has borrowed heavily from every language it has come in contact with over the centuries, and sometimes it picked up multiple meanings for similar sounds. For a while, Americans attempted to distance American English from its parent by changing everything from spelling and pronunciation to some meanings. Beyond that, language simply changes over time, of course. A word can begin to diverge in meaning and the word simply retains both meanings for a time, until the older form is forgotten by most.
Sometimes, though, a word retains its old meaning for a long time because it is used by a particular group of people for a particular purpose, while its new meaning grows more popular and well known in the public world. For example, most people know that the word "sanction" means to approve of an action or behavior. But there are cases, generally in law or business, where "sanction" still means a punishment or a judgment - being sanctioned could mean a fine or a jail term. Both meanings are perfectly legitimate and relevant in our society, only one is a bit less recognized, less used in common speech.
Now lately I have heard a good many people using the phrase, "It's just a theory." As it turns out, theory is also an autoantonym. In everyday use "theory" does indeed mean "a best guess." Random House Webster's College Dictionary's sixth definition is "a guess or conjecture." But its first definition is quite different: "A coherent group of general propositions used as principles of explanation for a class of phenomena." Just as sanction has a completely different meaning in the world of law, theory has a completely different meaning in the world of science. A theory is not by any means "just a theory."
People are often confused because science calls some things laws and some things theories. This isn't because laws are fact and theories are guesses. Law and theory are both the best explanation of two quite different areas. The National Academy Press, who advises our government on scientific matters, says, "Laws are generalizations that describe phenomena, whereas theories explain phenomena. For example, the laws of thermodynamics describe what will happen under certain circumstances; thermodynamics theories explain why these events occur. Laws, like facts and theories, can change with better data. But theories do not develop into laws with the accumulation of evidence. Rather, theories are the goal of science.”
Newton's Laws of Motion, for example, are only true under certain, very normal circumstances. They do not hold at the speed of light; that requires Relativity - also a theory, by the way, though thousands of scientists depend on it being true every single day. Neither do they hold at the subatomic level; that requires quantum mechanics - also a theory, and an autoantonym, while we're at it (in science, quantum means "very small" while in daily life it means "very big" - a quantum leap).
Oh, and atoms are just a theory, as are cells. And germs - that's the so-called Germ Theory of Disease. Which basically means that if you really believe that "just a theory" stuff, well, you can quite taking your vitamin C, washing your hands, and using all that anti-bacterial, anti-germ spray, soap, hand wash, and other cleaners. Because that nasty cold your coworker had can't "evolve" its way over to you - those germs are just a theory!
Newton's Law, the Second: The combination of Forces, called the Net Force, on an object are equal to the product of the object's mass and acceleration. The equation for this, and it's one that is used a lot, is: Fnet=ma. As it was explained in class a few days ago, a Force is defined as the measure of an interaction with an object. So, the total of the measures of the Forces acting upon an object are equal to the mass of the object multiplied by its acceleration.
There are several interactions which can affect an object. Three have already been mentioned. Friction occurs along the surface where the object moves, but in the opposite direction of the motion of the object. Air resistance occurs around the object as well, but at my current level of study, we pretty much assume that it doesn't exist - we study in a theoretical vacuum, as it were. (The same tends to be true of friction for now, as well.) The gravitational force is a pull that is directed toward a second object; at this level we generally only consider Earth as the second object and gravity, or free fall acceleration, as 9.8 meters per second per second. Weight is the measure of the net force required to prevent the object from floating off of the Earth. Weight, by the way, is not the same as mass, though they are related. An object's weight is equal to it's mass multiplied by gravity. So, 1 kg, for instance, does not equal 2.2 pounds... 1 kg weighs 2.2 lbs. Well, just keep that in mind for now... Tension is when a cord or string-like thing is attached to an object and pulled taut. The cord pulls on the object with a force directed away from the object and along the cord. And finally, the Normal Force, the confusing one. Because, oddly enough, normal doesn't mean normal, like average, or everyday. Those silly mathematicians (you know who you are!) actually mean perpendicular when they say normal. So, the normal force is the force that is perpendicular to the surface upon which the action is happening. It is the table pushing back up against the plate so that the plate doesn't just keep sinking on through and down to meet the planet.
Those are the basic forces, or at least as much as I've been taught so far.
Newton's Law, the Third: When two objects interact, the forces on the objects from each other are always equal in magnitude and opposite in direction. This is slightly different from the usual interpretation of "every action has an equal and opposite reaction." It has more to do with the interaction of two objects, and how they affect one another. If one object pulls on another, the second object pulls back with equal force and from the opposite direction. The same goes for pushing against as well.
Now, there's a funny thing about Newton's Laws. They don't actually work. Well, at least, not always. There are conditions where Newtonian Laws fail, and other ideas about motion have to step in and take over. But wait, you ask, I thought a Law was always, always, always true. The trouble with that thought, however, is that most folks are more than a little confused about the meanings of words like law, theory, and fact, as they relate to science. Sort of like the word "normal" which doesn't actually mean normal. More on that later, but for now, know that Newton's Laws cease to function when the objects in question are either very, very large, or very, very small. Things like planets and things that move near the speed of light don't work any longer according to Newton's Laws of Motion, they require Einstein's Relativity, instead. Tiny pieces parts of atoms require quantum mechanics.
And those are things of which I still know nothing... so here is where I get off.
My Physics instructor has not yet handed back our tests from Monday, so I don't know exactly how I did. I don't think it was very good, however. The test was over the first four chapters, Measurement, Motion on a Straight Line, Vectors, and Motion in Two and Three Dimensions. I had a pretty decent handle on things through vectors, but I got really messed up in Chapter 4. Uniform circular motion was fine, and I almost understood projectile motion but I don't think I ever managed to complete a relative motion problem on my own. So, the plan now is to add a projectile motion problem and a relative motion problem to my homework every day until I get the hang of them. I have this strange feeling that they will become harder and more important as we move forward...
At any rate, as no one really noticed, that means that this past Sunday's Sunday Brunch book review had to be pushed aside while I studied for said test. Just in case someone is waiting in breathless anticipation for my next review, I wanted to clear that up. <wink>
In other, much better news, my second ever technical document (a user guide for a web application) was sent to the client and accepted and approved with wild acclaim. Or, at least, no loud complaints. They seemed to like it, and didn't send back any changes. Go me!
