Recent content by cpman

I want to use orthogonal bearings to both simplify construction and to make the finished platform stronger. This is the same principle used in what are called vertical north section platforms. There are quite a few designs like this. I'm just not sure how exactly I should calculate the cuts for...

All that matters for this is lim_{n \to -\infty}(\arctan n) = \frac{-\pi}{2} as can be seen from the graph of y = \arctan x. If you graph the curve \frac{1}{x^2 -1}, you'll see that the area under the left side of that curve is not negative, unlike with y = \arctan x. The curve in question is...

Your first 2 steps are right, but it looks like you got a sign mixed up afterwards.

This one isn't too hard, but it is really cool: \int^{\infty}_{-\infty} \frac{1}{x^2 + 1} \, \mathrm{d}x

Hello. So, I'm designing an equatorial platform mount for my telescope at the moment. I'm also going to use it for another telescope that I'm in the process of building. I know that for both of the bearings, I can use small sections of two circles cut from a cone with an angle between the axis...

I've seen a paper that suggests that transesterfication of dimethyl oxalate over an SnO2 catalyst can be used to produce this compound with a ~22% conversion. I couldn't find the PDF of that paper, but I did find one on the production of SnO2 catalysts for transesterification here. Presumably...

This is because of its orbital inclination. This is the "tilt" of its orbit relative to the equator.The orbital inclination of the international space station is about 50°, so it orbits in a plane that is tilted 50° from the equatorial plane of the earth. Therefore, the highest and lowest...

Hello. I'd say that you are on a good track. I too am curious about learning, and knew many of those things in 7th grade. However, I would not suggest starting college early. I took the ACT when I was 13 (7th grade) to qualify for the Duke TIP program. I scored a 27 or 28 composite (I can't...

Firstly, sodium can not form a compound with aluminium. They are both metals, and except for rare cases, metals do not form compounds with each other. Secondly, the percipitate is probably Al(OH)3 like you suspected. Generally, Al(OH)3 is a fine whitish percipitate. However, if your electrodes...

This isn't chemical, it is biological. Mildew is a fungus, and fungi like moist, dark places. The high humidity simply facilitates the growth of the fungus.

Battery "water" is sulfuric acid (H2SO4). It turns green when it reacts copper hydroxide because copper (II) ions are blue in solution. From the reaction that should occur: Cu(OH)2 (s) + H2SO4 (aq) = CuSO4 (aq) + H2O (l) Copper (II) sulfate should be produced. In solution, this is a...

I'd say M57 is fantastic. It has a good surface brightness and looks amazing through my 10" Dobsonian. M1 looks pretty good from here in Austin. M17 is faint, but can be seen if you are experienced. M27 is also quite good. M31 is OK, but you don't get many details. M13 is fantastic! I spent...

A few things. Firstly, a few of the things that telescope comes with are ridiculous. The short focal length eyepiece provided will essentially be worthless. 215x on a 150mm telescope should almost never be used. It is pretty rare to get nights where the seeing allows better than 150x (in any...

Hello everyone! I'm really interested in learning forigen languages. I'm taking Spanish in school, and have achieved enough fluency to be able to participate in most conversations. Now, I'd like to start learning Russian. I've started with teaching myself the Cyrillic alphabet. Is this a...

With a mirror at least F/4.5 or faster, it is reasonable to assume that the eyepiece is less than 5'10", even with the mount, as the optical length of a 16" F/4.5 is 72". With compensation for the fact that the optical path is bent, the OTA will probably be close to 65" long. Unfortunately...