NeonBlack

Even the purest water you can get will still conduct electricity, although it has a very high resistance, 18.2 million ohm-meters if my memory is correct.

Here's a pretty standard one: [math]1^1=1^0[/math] Take the log of the equation: [math]ln1^1=ln1^0[/math] Equivilantly, [math]1ln1=0ln1[/math] [math]1=0[/math] This one is a little tougher. The imaginary number, [math]i=\sqrt{-1}[/math] Now, let [math]-1=-1[/math] We can also write this as [math]\frac{-1}{1}=\frac{1}{-1}[/math] Take the square root, [math]\frac{\sqrt{-1}}{\sqrt{1}}=\frac{\sqrt{1}}{\sqrt{-1}}[/math] [math]\frac{i}{1}=\frac{1}{i}[/math] Since by definiton, [math]i^2=-1[/math] then [math]1=-1[/math]

Speaking of Oedipus/Electra, I just saw this: Women like guys who look like dear old dad

You know... ... the gravity...

Why is rubber so rubbery?

Isn't that what intermolecular means? I thought that's what we were talking about the whole time!

I am just curious why the O's can't go together with these H's. Like I said, I haven't taken chemistry in several years.

It's been a long time since I've studied chemistry but I think some of those naked oxygens might be able to hydrogen bond, which is much stronger than that van der waals interaction.

I suggest always drawing a picture a free-body diagram with your problems, even if it seems trivial. If you had done this, you probably would have immediately realized that there is no x-accelaration and also avoided this mistake.

There are 2 big things about biology students, I think, that bother physics professors. First, "I don't need physics." Most biology students are required to take 2 semesters of physics to graduate. For some reason, a lot of them adopt the attitude that physics is not important and give the professors a hard time. Two, "I need a 3.9 to get into med school!" Many biology students are pre-med majors and will complain to the professor about a bad test or just about anything in the class which upsets them. I know a professor (my physics for engineering professor) who is one of the top bio-physics researchers in the US, but he simply refuses to teach physics for biology mainly for the two reasons stated above. If you are really interested in physics, I suggest taking a few problems to your professor's office hours. Show him that you are interested in physics and willing to work to learn the material.

Right. Exactly zero forces.

Epic thread! 10/10

After the ball has been thrown, how many forces are in the x-direction?

My friend's laptop looked like that after he dropped it and cracked the screen.

Thank you, bignose. Your explaination was very helpful. I know that this is the correct answer because now my simulation agrees with the theoretical result (this was actually a simulation problem for a class), but I am still not sure why, if I have two identical dice, I should consider 3&1 and 1&3 to be two distinct events.

I am having trouble with a probability problem: On average, how many rolls of a pair of dice will it take until the sum of the two dice is four? That is, I roll two dice. If the sum of the dice is not 4, I will roll again until it is 4. How many rolls should it take on average? I know that there are two possible ways to get a sum of four: either one of the dice is a 1 and the other is 3, or both of them are 2. There are 19 combinations of dice that do not results in a sum of 4, so the probability of getting a sum of 4 is 2/19. Now how do I figure out the expected number of rolls it will take to get a sum of 4? This problem is not even for a statistics class, so I have no idea what to do.

Mass is the same in all frames. This is the reason mass is called an "invariant."

Your intuition is correct. Normally, if two cars are travelling at the same speed, it will take longer for the heavier one to stop if they have the same breaking force. Is this problem, the cars are not stopping as a car would normally stop. They are locking their wheels and stopping by sliding friction between the tire and road, not by friction in the brakes. In this case, the heavier car will have 4 times more energy, but they stopping force will be 4 times greater and the stopping distance will be the same. I think they reason you are having trouble with this problem is tat it doesn't exactly describe a real world example. If cars stopped like this, the tires would not last very long.

1. Notice that [math]x-4+xy-4y=(x-4)(1+y)[/math] 2. Try integration by parts.

Once you have any experimental data, the data are useless without some interpretation. grimmy has taken some observations and interpreted them. As far as I know, the theory of evolution is not predictive and involves no math. It's not a very good theory in my opinion, but it's the best we have. Instead of saying "you are wrong," we should say "here's what you need to do to improve your theory." What you need for your theory is some numerical data. Then you have to interpret this data mathmatically and develop a theory consistent with your data. Then you can use your theory to make a prediction that can be tested. If your predictions are consistent with the new experiments, then you make another prediction and test it. If you do this a bunch of times, and everything work out, then you're in good shape. oh, and as far as I know, there is absolutely nothing wrong with any of Newton's laws.

Newton's laws are "inaccurate"?

In a freshman physics course, I came across the unit of microkilogram. I thought that was ridiculous. It seems like in chemistry, we always used non-SI units. I don't think I ever saw a cubic meter or a pascal in either one of my two semesters of general chem. It was always liters and atmospheres. Many SI units are just too inconvenient. I doubt this will change. Chemists will use liters or cc's, physicists will use eVs astronomers will use light years. Ask a biochemist how many microliters are in a "stere"

Yeah, knowing intervals is something anyone can learn with practice, not perfect pitch. Turn on the radio. If you have perfect pitch, you should be able to tell which key a song is in without any kind of reference. I once met a guy with an extremely good ear. He could identify pitches in almost any sound, for example, fundamental pitches in something like a car's engine.

I think this is pretty impractical. It needs some serious simplification at least. Look, you have s^2 - 1/4 s^2. Why not just write 3/4 s^2? Then if you do that, you have the square root of a square.

[math]\int \frac{sinx}{cos^2x}dx[/math] using regular substitution, let [math]u=cosx[/math]