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Overused Words Answered

This is to post your overused words. Interestingly, I definitely have to say interesting and definitely.

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uhhh.... ummm..... the... well... sorry, but..... you know..... thank you.

umm "the"... I say too many words too much, it used to be theory, every dumb idea I said was "in theory" to justify it. There are others but none are coming to mind. Also I got through that without saying "the" but I spelt it thrice...

Congratulations! You won! You guessed the magical answer! Yes, that is so true...

I didn't guess it, that one's just obvious... I'm still trying to not say that one, it's getting harder with each sentence, however I'm still rambling without say that word, very common, most common used in english, so I've heard anyway. Maybe it's time I stop before this gets so complicated I can't find a way around that word.

True, it's very hard not to say it. I realize now that I used it in my last comment...

Yes. It's a special word, and shall only be used when absolutely necessary. I should write an essay on how not to say that very special word. It would be a wonderful essay! I didn't even spell it once...

It's a difficult word to avoid for sure, but when one puts his mind to it such things can be done, granted you'll sound very odd while doing such a thing.

That is very true, it is very possible, but it is also true that it you will sound very odd. More challenges to add might be to not use it in contractions.

Sorry to spell that magical word... ...but I say 'therefore' too often in explanations. A few science tests ago I had a problem that asked me "What is the difference in momentum between two balls of equal SIZE when said balls are moving at a velocity of (ball1) 0m/s and (ball2) 100m/s?". I stated that difference in momentum between a stationary object and a moving object is impossible to calculate. I also stated that, according to relativity, you could say that those two balls had the same momentum in opposite directions. If ball one and two are equal in mass, you can say that ball1's momentum is equal to ball2's momentum, and each has a momentum of (whatever ball1's mass is multiplied by 50m/s). If you are moving towards ball1 (which is 'stationary') at 50m/s along the same plane that ball2 is moving towards ball1, it seems that ball1 is moving towards you at 50m/s, and ball2 is headed straight towards ball1 at an equal velocity.

I received a 90% grade, rather than 100%, for writing an answer that excelled to the point that even the teacher didn't understand it.

It's a pity that you were wrong. The question as posed implicitly specifies the reference frame to be used (namely, yours). In that reference frame, one ball is moving at 0 m/s, the other at 100 m/s. Since 100 m/s << 30000000 m/s, relativistic corrections are pointless and obfuscatory, and serve only to make you sound clever.

The difference in momentum is (100 - 0) m/s * mass. Since the mass of the two balls wasn't specified (or at least, you didn't quote it), the correct answer must be left symbolic: delta p = 100*m kg-m/s.

I would have given you 0 for that answer.

If it's m/s times mass then surely the difference is the mass of the moving ball considering the fact that any multiplication of zero will be zero... Though that is simplifying too much maybe, I think it works to some extent but not completely...

It's always best to keep the problem fully symbolic (algebraic) until the very end, then substitute known values. Otherwise, you could (not this problem, but others) end up in a situation where something looks like 0/0 or some other pathological case, but isn't really.

The problem statement, according to "chriskarr" is that the two balls are "the same size." I'm assuming that means the same mass (otherwise there is insufficient data to solve the problem at all). Then we have

p1 = m v1 (where v1 = 0 m/s)
p2 = m v2 (where v2 = 100 m/s)

dp = p2 - p1 = mv2 - mv1 = m(v2-v1)

Now substitute to obtain dp = (100-0 m/s) m = 100×m kg-m/s

Oh, by the way, the problem as written by "chriskarr" is also incorrect in using "velocity." Velocity is a vector quantity -- it has both a magnitude and direction. The correct term should have been "speed."

I see...

So as far as difference goes it's an obvious answer but an unknown quantity in algebraic form?

I suppose the problem is it's hard to see past any theoretical values... Though you're given V1 already, in that question.

Yes, exactly. The question as "chriskarr" wrote it is incomplete -- the mass of the balls isn't given. Otherwise it'd just be a subtraction, as you know :-)

Though even with masses, same or not then the same difference applies assuming the one with zero momentum has zero momentum... It would have mass but not momentum, where as the other would have a value of momentum...

For this special case, you're right. Zero is just zero :-) However, consider a very similar problem, with ball #1's speed 10 m/s, and ball #2's speed 110 m/s. The difference in speeds is the same, but the momentum difference will clearly not be the same as before if the masses are unequal.

Though as long as the masses are given the equation's still soluble isn't it? Even if it does get more complex... By the way are you any good with chemistry, not obscenely complex but reasonably so?

Absolutely! The problem is trivial (a grossly overused word in my field :-). My posting above is the whole solution, no matter what the mass and velocities are. Chemistry? Urgh...I can probably remember some of my undergrad p-chem, but I can't do o-chem at all. I know stoichiometry and the "theory" behind activation energy and rate-limiting intermediates, and I'm a firm believer in conservation of energy (so no, I won't help you design a water-fueled car :-).

>I'm a firm believer in conservation of energy That makes you an oddity around these parts...

That's ok then, I was wondering where the unsolvable came in...

It's a bit like squaring the circle, until I tried it, however some notions about using pi formula seem plausible, though it's impossible it's interesting because it seems so impossible...

I'll PM you, the physics might be need too, it's not exactly conservative but it's not perpetual motion...

I left out some bits with that comment. This particular problem, the one "chriskarr" wrote, is too simple to really need to be run through symbolically.

However, there are more complex situations, where you want to leave things in symbolic form, work through the algebra and calculus, factoring or combining terms, and only at the end plug in actual numbers. The main reason is that you could have a problem posed where the particular numbers coincidentally "cancel," but if you leave things symbolic, the cancellation doesn't cause problems.

Here's a specific example. Suppose, in the course of solving a physics problem, you find an expression that involves

m1 - m2
--_--_--_--_
m12 - m22

If the problem stated that m1=m2=50 kg, and you plug that in at the beginning, then you end up with 0/0 and you don't have a solution. But leave it symbolic, and you know m12 - m22 = (m1+m2)(m1-m2), so you factor the denominator and the expression above becomes 1/(m1+m2), and there's no division by zero at all.

Feel free to PM or use my Orangeboard, or even start a topic in Physics, if you want :-)

Sometimes you can fake your way to a passing grade with a worthless answer if you overwrite it. If it's sufficiently incoherent, but manages to use all of the right words in an obscure sort of way, a teacher might just give it a pass (rather than trying to untangle it).

Or they might give it a fail, because they have to untangle it.

That's true, but if you don't really know the answer to begin with, at least you have a chance.

Only one teacher pulled me on waffling but had to give me full marks for having expanded on all necessary points, at higher levels its useless...

most here know I overuse the word sorry way WAY too much :-)

I don't use it enough, is there a right amount though... I suppose if you use it and mean it every time it's not too much but meaning it and not using it's not good...

Oh, I mean it each time, it is just that I am being overly prophylactic most times.

...wow...ummm....nah, it's just too easy ;->

I was wondering if anyone was going to ;-)

I say "actually" too much.

You know, I actually don't agree, because, in all actuality, it's unneeded. You could simply say, realistically. And in other situations you could say, truly. In others you could say other things which have the same effect.

When writing essays, I usually say "however" too much.

It's like I state a point, and then just contradict it by saying however.

I say "for", right now in english we are doing mythologies. Gilgamesh wept FOR his brother, FOR he loved him very much and he was his only true companion.

I love Gilgamesh! Did you know that Daniel (in the Old Testament) was probably taught the epic of Gilgamesh? Man, I wish I could read Sumerian or Babylonian!

I LOVE GILGAMESH too! how old are you, you might go to my school... gilgamesh was wayyyy better than chuck norris. He was like 16-20 feet tall according to the book SPOILER ALERT I can't believe enkidu dies!!! crycry

I'm probably not in your school. I read Gilgamesh in high school, 20 years ago, and then again in college 10 years ago, and then again last year. I'll probably have my kids read it next year (they are home-schooled). I like "flood stories" from the various cultures. The similarities and differences are fascinating!