Adam

I was helping my girlfriend with her math HW and was surprised when one stumped me. I couldn't figure out how to cancel out terms in the limit to make it calculable without using L'Hopital's rule, which her class hasn't covered.

The limit:

lim(x->π/2) 5(sin(x)-1)/(cos^2(x))

Is there some trig identity that is useful here?

Thanks.

I want to get a gain of ~100, but it is limited to about 13.7 V because the source voltage is 15 V. Why is that? Why can't I get more than 13.7 V output?

http://news.yahoo.com/s/afp/20101119/pl_afp/natosu...

How is this news? It's a politically biased article. Do you really think Obama has control over how he is transported as an ambassador of the US? Why would the president be transported in a fuel-efficient car without armor or sufficient horsepower?

http://news.yahoo.com/s/afp/20101118/ts_afp/usspac...

Scientists are supposedly perplexed by the fact that the star and its planet are both made of light gases. It doesn't seem that amazing to me. Here are my ideas as to why this happened:

- It was a binary star system that had one dominant star leech off most of the mass of the other star.

- The rocky planets that *were* there before had been engulfed by the star during its red giant phase. Imagine if every planet up to Jupiter were engulfed by the Sun. It would also seem that our solar system contained too little heavy matter.

- The heavy matter is there after all, we just haven't found it.

Do you think any of these theories are likely? What are your thoughts?

If I try to change it in my settings, it actually shows the picture I WANT as selected. Yet I submit, and this stupid (!) is my picture. Not to mention it changed on its own in the first place. Explanations please??

I drive my parents' dark green '96 Dodge Grand Caravan. It is not a great car, but I want to make the most of the situation, so I am trying to give it some personality. First off, I need to give it a good name, but I can't think of any good ones. It is an old, run-down van, which I have to drive gingerly so that I don't break it (for real). Any help?

Some things I've thought of:

Eore

The Barge

The Shuttle

The Green Machine

Cannot time have multiple dimensions as well? I know this seems abstract. Could we be able to not only move forward through time, but backward, up and down, and side to side through time?

Speaking only about stars that are second-generation or later. Why do they still fuse hydrogen first? One would think that the hydrogen would float to the outer layers, while the heavier elements would sink to the middle to be fused. Our Sun contains hydrogen and helium, but unless I am mistaken, there is hydrogen present at its core that is fused to make energy, rather than simply sitting on the surface. Why?

Was it part of a meteor shower, or was it just a stray one? I didn't have time to watch for long.

Usually I hear that one simply has to "rewind time" to find that the Universe was once extremely small based on the fact that it is expanding. That fact alone can't be the only reason cosmologists believe the Universe was once this small -- if I see a balloon expanding, I usually don't infer that it started at the size of an atom!

So, according to modern theory, what was the size of the Universe at time zero (or at the earliest possible unit of time)? If the Universe is just the interior of a black hole in some other Universe, does this mean the Universe started fairly large as the radius of the black hole and simply expanded?

Are you the type of person that tends to ramble on when responding to a question, or are you more "short and sweet"? A for the first option, B for the latter.

http://i853.photobucket.com/albums/ab93/bltsandwic...

Where does the energy of the sound waves go if it is not transferred to other surrounding particles? Does it simply circulate within the object (e.g. the spacesuit surrounding an astronaut attempting to speak), or does it radiate outward somehow?

Would the planet slowly drift apart, or would internal pressure cause an explosion?

Or can it vary?

And what could one do in order to market himself?

Other than expanding spacetime being a theory that solves many problems, what makes it the real winner over other theories? Could the overall distancing of matter from other matter just be a force within space, not a force of space?

This happens a lot, as I tend to mash my eye up next to it... I should really stop that :) It sticks just like a tongue to a stop sign on a cold day.

I think I was about four years old when I had my first exposure of outer space: I was watching Blue's Clues, and there was an episode in which Blue explored the solar system. I remember being extremely interested. When I was around 7 years old, I grabbed a couple DK science books about the solar system. I just looked at the pictures (and when I was able to, I read the captions as well). Now at age 16, I am using a telescope for the first time.

What's your story?

I'm not sure whether these objects are moons or stars. I'm pretty sure they're moons, though, because they don't seem to be point-like. How can I differentiate between background stars and moons, and if the objects are moons, which moons are they?

Thanks!