The Small Rants Thread IX: Leaping into the Well of Darkness

[Raineh Daze]

It's very useful.  You can usually figure out the equations from the units.  You usually can't figure out the constants from it (like energy is 1/2 mv^2, units don't tell you that 1/2), but often you can figure those out in the calculus based physics (the 1/2 comes from the fact that energy is an integral, which ends up being 1/2mv^2.  And it's even MORE useful for word problems!  You read the problem saying "here's what I have, I need to get to these units, how do I get to those units?"

Fortunately, no calculus in my course. How lucky.

Either way, my point was that unit matching is great for question-checking or working out which equation you need... not so great if you need to write a paragraph on what all these numbers actually mean.

[dman11235]

ah.  Can you give me an example?

[Raineh Daze]

ah.  Can you give me an example?

I can give you one of my exam papers, even. Think that was it, at least.

[dman11235]

....knowing your units LITERALLY answers that first one   That is a REALLY good test.  And knowing your units does help on a good number of those.  Specifically the ones that require a look at calculation (even if you don't have to calculate).

[Raineh Daze]

....knowing your units LITERALLY answers that first one   That is a REALLY good test.  And knowing your units does help on a good number of those.  Specifically the ones that require a look at calculation (even if you don't have to calculate).

There're still the questions that require being able to explain the physics and not just comprehend unit cancelling.

But as I said, I got an A in Physics. Given that my coursework included the cheerful 'I can't get a magnetic response off of my electromagnet' and 'the wavelength of green light is orange', this isn't exactly a bad result.

[dman11235]

...how...

The electromagnet is easy to explain, faulty wiring can easily break one.  Heck, even non-faulty wiring that is arranged wrong can (simply have the current run an equal number of times in the opposite direction, and you have an equal magnetic field with an opposite direction, effectively canceling the field, though it would be a dipole-ish-thing).

The....light....how?  Only thing I can think of is that it was mislabeled...or miscalculated, or the error was very large (well, relatively).  What experiment was that one?

[Raineh Daze]

I managed no magnetism with about five different power supplies and many different coils of wire. Also a coil of wire with an iron core. No measurable magnetism!

Light? I was very careful with the diffraction (it was based on beam width or something) and the measuring. The result: everything had a very neat range bar, but the range was squarely within orange wavelength. I was baffled, gave up, and wrote barely anything for that submission because... what else was there to do with things being that wrong?

[dman11235]

hmm...

you may have had a weak magnet setup...that's...not making too much sense as to why you had no detectable magnet...wow...

So the light looked green, but math said it was orange?  Well, with diffraction, if you're looking at beam width, I don't think that's going to get you good data....you need to look at the fringe spacing, and distance from grating to the backdrop.  It's also not the most accurate method, inherently.

[Raineh Daze]

I at one point got a magnetism less measurable near the magnet than in thin air. I think that was the point that I declared I'd found a way to destroy magnetic fields.

Fringe spacing and distance! That was it! I got very precise results, only they were several hundred nanometres out.

[littha]

I at one point got a magnetism less measurable near the magnet than in thin air. I think that was the point that I declared I'd found a way to destroy magnetic fields.

Fringe spacing and distance! That was it! I got very precise results, only they were several hundred nanometres out.

In a similar science fail I once managed to set what was supposed to be distilled water on fire during a chemestry lesson...

[trappedslider]

So at what point during physics do you learn how to use a crowbar? 

[dman11235]

NOt until you start making your own equipment.  You generally don't need one until you have large builds like particle accelerators, and they don't give you your license until you demonstrate proficiency with one.  I won't get mine until I start teaching.  I already have it designed and submitted, and I went old school, with FERMIlab making mine.  That's what the particle accelerators REALLY do, make us physicists crowbars.  Mine's going to be bismuth!

@littha: Sodium?

[Raineh Daze]

... I have no idea how I managed to so actively get no results.

I think my writeup for that experiment was basically working out electromagnetic laws based on "Well, if my results had made ANY SENSE".

[littha]

NOt until you start making your own equipment.  You generally don't need one until you have large builds like particle accelerators, and they don't give you your license until you demonstrate proficiency with one.  I won't get mine until I start teaching.  I already have it designed and submitted, and I went old school, with FERMIlab making mine.  That's what the particle accelerators REALLY do, make us physicists crowbars.  Mine's going to be bismuth!

@littha: Sodium?

My guess is that it was contaminated with some of the ether we were using in a different part of the experiment but I cant be sure.

[dman11235]

ah, that would make sense.  That stuff's easy to get places you don't realize.

[trappedslider]

NOt until you start making your own equipment.  You generally don't need one until you have large builds like particle accelerators, and they don't give you your license until you demonstrate proficiency with one.  I won't get mine until I start teaching.  I already have it designed and submitted, and I went old school, with FERMIlab making mine.  That's what the particle accelerators REALLY do, make us physicists crowbars.  Mine's going to be bismuth!

@littha: Sodium?

Aslong as they also check you on military weapons and such lol

[Kuroimaken]

STOP MAKING SCIENCE AND MATH LOOK SO EASY!! 

...sweet merciful Jebus, I feel so stupid sometimes.

[Amechra]

STOP MAKING SCIENCE AND MATH LOOK SO EASY!! 

...sweet merciful Jebus, I feel so stupid sometimes.

But it totally is if you have the talent for it. It's just that you need to know the preceding steps before the next step makes any sense.

You just need to take a few more levels in Egghead instead of taking more levels in Badass. Serious, Kuroi, do you really need more levels in Badass?

[phaedrusxy]

I at one point got a magnetism less measurable near the magnet than in thin air. I think that was the point that I declared I'd found a way to destroy magnetic fields.

Fringe spacing and distance! That was it! I got very precise results, only they were several hundred nanometres out.

In a similar science fail I once managed to set what was supposed to be distilled water on fire during a chemestry lesson...

I decided to set up an electroysis device at home when I was a kid, and I collected the hydrogen in a mason jar. Then I thought it would be fun to poke a hole in the top, and make a lantern. After I lit it, for a few seconds it worked as planned... then of course as the hydrogen rushed out, air went in to fill the void... and the whole thing exploded spectacularly.  Luckily no one was hurt.

[Amechra]

Geez you guys, all I've ever been able to do was break compasses.

Stupid things keep pointing to magnetic NNE or whatever.