Volts: think of this as describing how badly electrons want to get from point A to point B. This expresses how much energy is removed from every unit of electrical charge that flows from point A to point B. Since each electron carries a fixed amount of electrical charge (this is a fundamental property of the electron), you can work through the math from volts to an actual amount of energy (foot-pounds, newton-meters, BTU, whatever unit you want) being removed from each electron that flows from point A to point B (with that energy being used to heat your toaster or power your table saw or light up your desk lamp).
Amperage: how rapidly electrons are actually getting from point A to point B. An ampere is a unit of electrical charge flowing per second. Since each electron carries a fixed amount of electrical charge, you can work through the math from amps to an actual number of electrons per second moving from point A to point B.
Watts: the product of volts and amps. Since volts expresses energy removed from each electron that flows from point A to point B, and amperes expresses how many electrons are flowing per second, the product is energy per unit time, which is referred to as power. If you multiply X volts by Y amps, you get X*Y watts, where watts is the SI unit for power. Power can be expressed in other units too, like horsepower, which is more commonly used to describe the mechanical power output of engines. 1 horsepower is about 746 watts; a 300-horsepower engine puts out about 224 kilowatts of mechanical power, and a 100-watt lightbulb consumes about 0.134 horsepower of electrical power. An electrical motor rated for one horsepower will put out about 1 horsepower of mechanical power from its spindle, and will consume somewhat more than 746 watts of electrical power (since it’s not 100% efficient at converting electrical power to mechanical power), with the difference being dissipated as heat in the motor’s electrical components and bearings.
I just take the second digit and subtract 2. 16:00? 4 PM. 22:00? 10 PM. Yeah, you have to do a little mental gymnastics to remember when to drop the leading one or subtract 1 from it, but that’s pretty easy for me to remember.
For some reason, I can’t subtract twelve quickly, but I can subtract 2 from the second digit like a whiz.
Economics, and anything to do with investing, taxes, and money stuff.
I cannot grasp it. I have this stuff explained to me slowly and carefully and I get it, I think, but then it’s gone. We went through a mortgage refinance recently and I really have no idea what went on. I think maybe I understood at the time, but my brain won’t retain that stuff at all.
I’m a professional scientist and aced every math class I ever took. Yet I still have no idea how I ever manged to pass any of my three physics classes, especially the one on electromagnetism. I could understand the background well enough, but when it came time to work out specific problems, it was like all the words suddenly turned into Russian.
“Shorting” a stock or fund. I read and re-read the Wikipedia and Investopedia descriptions, and I can’t grasp it at all. I get the general idea - you’re betting against a security rather than with it, but the internal mechanism is all just a blur.
I guess I take my music ability for granted. It sounds odd to me that people lack the innate ability to feel the start of every measure. And keys! I love keys! Minor keys, please.
My achilles heel is accounting. I got an A in the first semester (Accounting I), because it was summer school and the semester was only a month long. Then I tried to take Accounting II during the normal school year and failed spectacularly. Not only did everything from the first class totally fly out of my head after the final, but I was incapable of retaining information beyond 30ish days back in Accounting II. I bombed the final, it was embarrassing. Debits, credits, how the hell can anyone retain any of this? I aced calculus, no prob. Eff accounting, though!
Similarly, I developed a bad mental block about vectors in my freshman Physics I class. Vectors are pretty much the reason why I changed majors.
Same here. And I grew up in a religious family. One of my parents was ordained, even.
The other thing I can’t wrap my mind around is pinochle. I’ve learned to play 5-6 times, but it just doesn’t stick. Even with a cheat sheet listing all the combinations of possible plays or melds or runs or whatever they were, I was lost.
It doesn’t help that Missus Coder loves the game, and would happily play a couple of times a week if possible. Euchre, cribbage, and other card games are fine. Well, except bridge. I’ve been afraid to even TRY that one. I’d need a cheat sheet the size of a table to play, I think.
:smack: You, sir, have just changed my life. I never thought about it before - 24 hour time was never taught in school, so I never learned a trick like that. You know, a trick like Never Eat Soggy Weiners.
Um, to make myself look a little less stupid, I did pass the top high school math class here!
Thanks. That helps, but I think one problem I have is the concept of electrons flying around. I mean, I think of electrons spinning around the nucleus of an atom, not flying around on their own.
I’ll have to study your post in more detail and see if it sinks in. Khan Academy seems to have some information on voltage, capacitance, etc, so I’ll check that out as well.
Just like magnets have a north and south pole (negative and positive / opposites attract, likes repel), well the electron is like the negative pole of the magnet, and the proton it zooms around is the positive pole. Also called charges.
However, electrons can flow (current) from atom to atom, freely. Now, let’s say you rub your feet all over the carpet and touch a doorknob, we all know you’ll get a zap of static electricity.
This is because, typically you have (close to) a net charge of zero. That is, you should have as many free-wheeling negative electrons, as you do stubborn, stationary protons. But when you started rubbing your feet on the carpet, the carpet’s electrons were getting all shuffled around, and your body took on far more electrons than you have protons available for. So you are now negatively charged. This is why the hairs on your arms stand on end, there’s a glut of negative electrons all repelling each other, but they have nowhere to go… yet. So, When you touch something as conductive as metal, all those electrons with no home, have now found one, and are immediately attracted to the protons in the knob, creating a tiny spark as this transfer surges into the knob, and gives off photons (light and heat, or resistance).
You’re now neutral again, so stop being so negative.
As for me, anything financial. Taxes, mortgages, interest rates, etc. I sort of get the idea, but it’s infuriatingly boring and seemingly needlessly complex, my eyeballs just go white. And the stock market, investment options, retirement portfolios? Just leave me alone!
Ah, centripetal force. Centripetal force is any force that keeps something going in a curved path. Things normally will go straight unless there’s something keeping them turning. That something’s centripetal force- gravity is the centripetal force keeping the earth going around the sun and the moon going around the earth. If you swing a dead cat around your head, the centripetal force is provided by the tail as it holds the rest of the cat in its orbit around your head, unless you’re swinging the cat by its head, in which case the cat’s neck is providing centripetal force.
“Centrifugal force” is really just inertia opposing the centripetal force.
Now you’re getting into something I’ve never understood. Why does the scraping action transfer so many more electrons from the carpet to your feet than from your feet to the carpet?
For me it’s history. I have read a number of fascinating history books and I can’t really remember a damned thing about them. I really couldn’t even tell you why World War I came to be (the assassination of Archduke Ferdinand, yeah, but I don’t know why he mattered so much.) I received a National Geographic Book of World History - awesome stuff, very basic. I could sort of vaguely tell you there were Romans and there were Turks and sometime before that Mongols took over the East, but it’s all a jumble and I really should just give up.
