delirium happy

Just keep on trying till you run out of cake

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Interview thingy
delirium happy
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burr86 did one of those interviewy type things for me. I'm not going to offer to ask questions of the rest of you though, because thinking up questions is hard. But here are the answer to his questions.

1. If you could articulate your guiding principle in one sentence, what would that sentence be?

Excessively long and wordy. Though if you insist on a single guiding principle, I think that "never treat people as things" covers a whole lot of ground, and that you can extrapolate a great deal from there.

2. What's a valuable skill that you've learned from having done Support?

For those who don't know, I quit doing LJ support the other day (yes, again; but I rather suspect that it will be for good this time). I think that the biggest skill that I learned was self-confidence and self-reliance. Put me in that sort of structured environment, and it's easier for me to see that, hey, I really am that damn good, aren't I? (and oh so modest as well)

3. What are your thoughts on calculator usage by students; are we teaching people to be too heavily calculator-reliant?

My main thought can be summed up as "argh! stab! gnash! whine! facedesk! scream! explode!" I'm not a fan. Calculators have their uses, certainly, and I wouldn't want to be without mine, but calculators make people stupid. Time after time I see students blindly plugging numbers into their calculator, and then writing down the answer without giving a second's thought as to whether or not it's actually plausible. I see people going straight to their caculators and plugging the numbers in rather than doing simple algebra to vastly simplify the problem, and ending up with rounding errors the size of France. I see them wasting huge ammounts of time reaching for their calculator to work out 112-28, or 40*25, or [3sqrt(2)]^2 or something else so mind-bogglingly simple. When you rely extensively on a claculator, you stop "seeing" the numbers, and everything becomes so much more difficult. It also means that you're totally screwed when you encounter a freaky problem that your calculator won't handle, or when its batteries run out.

4. Where do you see yourself in three years?

I'm honestly not sure. If I had to pick any single possibility, then I'd say that the most likely one would be that I'd stil be at Lancaster University, and would be studying a PhD, but I'm hardly terribly confident of that. On a personal level, I haven't a clue. I guess I'll still be thoroughly screwed up in the head, but probably better able to deal with it. Who knows though. For all I know, I'll change my name to Norman, move to Nicaragua and live in a monastery.

5. Suppose you had two blocks of equal mass, one traveling to the left at a velocity of 24 m/s and the other traveling 45° below the x-axis at a velocity of 48 m/s. Find the amount of kinetic energy lost if the two blocks collide inelastically.

I was trying lots of clever ways to do this, with gailean transforms and centre of mass frames of reference, and such like, to try to give a general formua for the set of possible outcomes, based on a parameter theta. I kept making silly mistakes though, so I'm going to go with the simplest answer, which is to say that there are an essentially infinite number of different possible inelastic collisions, and that an arbitrarily low amount of kinetic energy can be lost (take, for instance, two snooker balls colliding; this is clearly inelastic since sound energy is produced, but the paths the balls follow are near as damnit to the ones you'd get in an elastic collision).

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Love your answer to number 5, even if I have no freaking clue what it's all about. :)

Aha! a cunning opportunity to try to explain physics to people. Hurrah!

OK, you have this thing caled energy, which is used in a similar way by physicists as it is my normal people. There are lots of different kinds of energy though: there's kinetic energy (energy of moving things), potential energy (if you lift a ball up to the top of a hill, then it has the potential to fall down), heat energy, chemical energy, sound energy, and so on.

One of the fairly fundamental laws of physics is the principe of conservation of energy, which means that total energy always stays constant; you can't create or destroy energy, you can only transform one type into another type.

So, you have two blocks hurtling along towards each other, and at this point they have a whole lot of kinetic energy. Then if they hit each other, this kinetic energy might get tranformed into some other form of energy. It might make a big noise, or the bits of the blocks that hit might get hot, or they might be deformed, or whatever.

There's a special type of collision though, caled an elastic colision. This is a colision where none of the kinetic energy gets converted into other types of energy. These are particuarly useful because in that case, it's possible to predict exactly how the two bocks will travel on after they've collided (you have to use another law of physics, called the principle of conservation of momentum, and it all works out relatively simply).

The probem is that there's no such thing as an elastic collision in the real world, unless you go down to the scale of elementary particles. In reality, whenever two things hit each other, some of the kinetic energy does get converted to other types, and you get an inelastic collision.

As such,it's much, much more difficult to predict the exact behaviour of two objects after they hit each other. Instead of just having one possible outcome, you end up with a whole bunch of different possibilities. What I was trying to do at first was to say "if this is the case then that will be the result", only in a mathematical way. That didn' work out though, because I kept fluffing my calculations.

What you can do instead though is say that in a lot of cases, only a litte bit of kinetic energy will be converted to other types. That was the snooker ball analogy. When snooker balls hit each other, you get a tiny little bit of sound given off but the rest of the kinetic energy stays as kinetic energy. This is good, because you can pretend that it's an elastic collision, and the answer that you calculate is so close to being right that it works well. The bigger the loss of kinetic energy, the bigger the range of possible outcomes.

Hopefully that all makes some sort of sense.

You lost me at snooker ball. :D I understood the conservation of energy and momentum - covered a lot of that in Physics and Astronomy. But what the heck is a snooker ball?

(I'm just teasing, you know. Thanks for explaining the elastic collision.)

Was that with a calculator, or without? *looks suspicious*

Without, in about 10 seconds.

Congratuations. You are smrt. You pass the internet.

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