## Search found 209 matches

Sun Jun 26, 2011 10:40 pm UTC
Forum: Science
Topic: Why do we measure half-life instead of just life?
Replies: 62
Views: 14377

### Re: Why do we measure half-life instead of just life?

I'm sure there's some rudimentary explanation that escapes me, but ever since I first heard the term, I wondered to myself, why do we measure atomic decay or whatever in half-life, instead of whole life? I can't think of a reason half-life would be preferable. It's exponential decay. "Whole li...
Sun Dec 27, 2009 8:37 pm UTC
Forum: Mathematics
Topic: Function problem
Replies: 11
Views: 1463

### Re: Function problem

Also, if you graph f(x) - x, it should reach a maximum at x = e, (because that's where f(x) crosses the line y = x), so that means the derivative of that function at e i s 0. f'(e) - 1 = 0 f'(e) = 1 f(x) - x doesn't have a maximum on (1,inf). Both f(x) and -x are strictly decreasing. You can figure...
Sun Dec 27, 2009 8:03 pm UTC
Forum: Mathematics
Topic: Graphing Problem
Replies: 9
Views: 1874

### Re: Graphing Problem

Ended wrote:Wolfram Alpha makes a reasonable attempt.

Code: Select all

http://www.wolframalpha.com/input/?i=plot+z%3D%28x^%281%2Fy%29%29*%28y^%281%2Fx%29%29

This works better:

Code: Select all

http://www.wolframalpha.com/input/?i=countourplot+1%3D%28x^%281%2Fy%29%29*%28y^%281%2Fx%29%29
Wed Dec 23, 2009 12:54 pm UTC
Forum: Science
Topic: Think: What color do you associate Chemistry with?
Replies: 97
Views: 10094

### Re: Think: What color do you associate Chemistry with?

Anubis wrote:
Twistar wrote:Social studies is definitly green though. I mean.. what color is history other than green?

No, history is definitely brown.

History is yellow. Brown is arts and literature.
Sat Dec 05, 2009 6:47 am UTC
Forum: Mathematics
Topic: Non-deterministically infinite iterations
Replies: 15
Views: 1204

### Re: Non-deterministically infinite iterations

First, the part about rolling a bunch of dice simultaneously is irrelevant. The problem is equivalent to rolling the dies individually one after another. This transforms the problem into a bog-standard risk of ruin calculation. There is some probability P(k) that you will bust a bankroll of k dice e...
Mon Nov 09, 2009 7:16 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: RELATIVITY QUESTIONS! (and other common queries)

I think people here have an antiquated conception of inertia. In classical mechanics, m is called inertia because it is inversely proportional to acceleration, by the simple equation: \textbf{F} = \frac{d \textbf{p}}{dt} = \frac{d}{dt} m \textbf{v} = m \frac{d \textbf{v}}{dt} = m \textbf{a} Clearly...
Sat Sep 19, 2009 5:24 pm UTC
Forum: Forum Games
Topic: Sheep!
Replies: 5
Views: 1128

### Re: Sheep!

Well, I've only got four entries for this. Is there anyone else who would enter if I wait a while?
Fri Sep 18, 2009 9:27 pm UTC
Forum: Forum Games
Topic: MTG Play-by-post (and other games too)
Replies: 21
Views: 2852

### Re: MTG Play-by-post (and other games too)

Any deck construction rules? T1? T2? Extended?
Fri Sep 18, 2009 6:58 am UTC
Forum: Forum Games
Topic: Sheep!
Replies: 5
Views: 1128

### Re: Sheep!

24 hour notice. Get your entries in if you want to play!
Thu Sep 17, 2009 9:27 am UTC
Forum: Forum Games
Topic: Sheep!
Replies: 5
Views: 1128

### Re: Sheep!

scrovak wrote:But you said un numbered so how are we supposed to....

Or do we just type the answer for each question (without a number) straight down?

Yes. The answer list in the PM should look like this:

bat
cat
mat
hat
etc.
Thu Sep 17, 2009 7:48 am UTC
Forum: Forum Games
Topic: Sheep!
Replies: 5
Views: 1128

### Sheep!

Here's how this game works. There's a list of questions at the bottom of the post. You PM me your answers to these questions in an unnumbered, return delimited, list (this is for compatibility with the automatic scorer I'm using). For each question, you get one point per person who answered the same...
Wed Sep 16, 2009 1:52 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: So why can't an object go faster than light?

The problem with your idea is that a constant force doesn't provide a constant acceleration once you get into relativistic speeds. Yes, you will always have a >0 acceleration, but it will get smaller and smaller the faster you go, with the result being that you asymptotically approach the speed of l...
Wed Sep 09, 2009 10:52 pm UTC
Forum: Mathematics
Topic: Practical Explanation for calculating the area under curves
Replies: 17
Views: 2368

### Re: Practical Explanation for calculating the area under curves

The value of a function at a point describes the height of a small rectangle that describes the rate of change of the area under the curve. Sorry for bumping this, but I'm afraid I'm misinterpreting your statement. Even with the risk of sounding silly, I must ask how does the rectangle describe the...
Fri Aug 28, 2009 7:16 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: Help with special relativity

Simple, yes? Now, if you want an additional twister, consider what happens to B's clock from A's perspective. (Remember, B is moving away from A at 0.87c, so A perceives B's clock to run at half the speed of his own...) # This is the bit I want to know, what happens to space and time, from each per...
Wed Jul 29, 2009 8:13 am UTC
Forum: Science
Topic: Tiny Dimensions
Replies: 36
Views: 3149

### Re: Tiny Dimensions

doogly wrote:Unless it's something sneaky like a Hausdorff dimension or a Krull dimension.

Is a Krull dimension one that is shaped like a curved 5 pointed star like this?

Thu May 28, 2009 11:53 pm UTC
Forum: Logic Puzzles
Topic: Two Numbers
Replies: 2
Views: 759

### Two Numbers

There are two distinct whole numbers x and y. They are both greater than 1. They sum to less than 100. Person A knows x*y, but not x or y. Person B knows x+y, but not x or y. The following conversation takes place (neither person lies): A: I don't know what x and y are. B: I knew you'd say that. A: ...
Mon May 11, 2009 8:54 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: RELATIVITY QUESTIONS! (and other common queries)

You can derive the Lorentz transformations from that principle, and then there you go. At greater length: http://en.wikipedia.org/wiki/Introduction_to_special_relativity (It seems pretty OK but I just skimmed it so usual wiki caveats) Right, but the Lorentz transformations don't strictly exclude sp...
Mon May 11, 2009 7:07 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: RELATIVITY QUESTIONS! (and other common queries)

doogly wrote:The fact you cannot exceed the speed of light follows from its being constant in all reference frames.

How does this follow?
Mon May 11, 2009 3:34 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: RELATIVITY QUESTIONS! (and other common queries)

gmalivuk wrote:It never gives an answer higher than c for physically possible velocities u and v.

But the post that seladore was responding to was talking about tachyons. I was under the impression that tachyons hadn't been ruled out as physically impossible, just that we have no reason to believe they exist.
Mon May 11, 2009 2:57 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2962
Views: 731598

### Re: Special relativity discussion/questions

What about when we cross over to the imaginary numbers, by going faster than c relative to a body? Would that mean that each body would observe the other body in backwards motion while they move forward through time? If backward/forward is relative in this way, does that mean that slower than c/fas...
Sun May 10, 2009 11:18 pm UTC
Forum: Logic Puzzles
Topic: Traveler's Dilemma
Replies: 833
Views: 88606

### Re: Traveler's Dilemma

"The fact that 100 is dominated by 99, and therefore will never be played by either player, is true. This is a valid argument, and its conclusion that all cases in which either player plays 100 are impossible is a correct one. The fact that both players wll always play the same number, and the...
Sun May 10, 2009 5:46 am UTC
Forum: Logic Puzzles
Topic: Traveler's Dilemma
Replies: 833
Views: 88606

### Re: Traveler's Dilemma

"The fact that 100 is dominated by 99, and therefore will never be played by either player, is true. This is a valid argument, and its conclusion that all cases in which either player plays 100 are impossible is a correct one. The fact that both players wll always play the same number, and the...
Sun May 10, 2009 3:12 am UTC
Forum: Logic Puzzles
Topic: Traveler's Dilemma
Replies: 833
Views: 88606

### Re: Traveler's Dilemma

"The fact that 100 is dominated by 99, and therefore will never be played by either player, is true. This is a valid argument, and its conclusion that all cases in which either player plays 100 are impossible is a correct one. The fact that both players wll always play the same number, and the...
Tue Apr 14, 2009 12:28 am UTC
Forum: Forum Games
Topic: Sheep!
Replies: 12
Views: 1070

### Re: Sheep!

Ok, looks like there's enough interest. I'll post the questions as soon as I'm done with them.
Sat Apr 11, 2009 9:02 pm UTC
Forum: Forum Games
Topic: Sheep!
Replies: 12
Views: 1070

### Re: Sheep!

Ah, so it's like Trivia? Hmm, I might be up for it, but I doubt I have the time this week or next. Sorry. Sort of. The idea is to try to guess what you think everyone else will be guessing. It doesn't take very much time. All you have to do is fill out answers to 15 - 20 questions and PM them to me...
Sat Apr 11, 2009 8:46 pm UTC
Forum: Forum Games
Topic: Sheep!
Replies: 12
Views: 1070

### Re: Sheep!

Some example questions from a sheep game on another site:

1. Name a TV news anchor

2. Name a type of pasta *besides* spaghetti

3. Name a classic arcade game *besides* PacMan

4. Name an NFL team that has had at least one dynasty

5. Name a southern U.S. city
Sat Apr 11, 2009 8:42 pm UTC
Forum: Forum Games
Topic: Sheep!
Replies: 12
Views: 1070

### Sheep!

Who wants to play a game of sheep?

Here's how you play. I post a list of questions, then everyone who wants to play PMs me their list of answers. You get one point for each other player that gave the same answer that you did. Correctness doesn't matter. Highest score wins. Any takers?
Mon Nov 17, 2008 4:45 pm UTC
Forum: Food
Topic: Beer is proof that God loves us and wants us to be happy.
Replies: 1738
Views: 368236

### Re: Beer is proof that God loves us and wants us to be happy.

On the other hand, some IPAs are very bitter because they use a broad spectrum of hops in puruit of complex flavors. The best example is Stone's Arrogant Bastard Ale which is very bitter, but has more complexity to it than any beer I have ever tried. If you find it in 22oz botlles, one should be en...
Sun Nov 16, 2008 5:19 pm UTC
Forum: Science
Topic: If a knight gets struck by lightning
Replies: 13
Views: 5638

### Re: If a knight gets struck by lightning

at least for the thunder, that shouldn't be any stronger than in a regular lightning strike. The heat is a possibility, because P=V 2 /R, so with V is large and R is small, it could be pretty hot. No. The total resistance is still high, the air above have a hell lot of resistance. P=RI 2 means litt...
Fri Nov 07, 2008 5:56 pm UTC
Forum: Language/Linguistics
Topic: Think Before Naming Your Child
Replies: 1622
Views: 353261

### Re: Think Before Naming Your Child

A friend of mine named his daughter Galadriel. This isn't such a bad name, though it doesn't shorten easily. However, he had said that if the kid was a boy he would be named Feanor, which would be pretty terrible.
Fri Oct 24, 2008 4:17 am UTC
Topic: 0493: "Actuarial"
Replies: 95
Views: 22274

### Re: "Actuarial" Discussion

Is it 2038 because that is when R2-D2 and C-3P0 will crash due to running on 32-bit UNIX time?
Wed Sep 24, 2008 8:52 pm UTC
Forum: Movies and TV Shows
Topic: Has anyone seen "The Big Bang Theory"?
Replies: 214
Views: 91386

### Re: has anyone seen "the big bang thory"?

Monday's episode was possibly the funniest thing I've seen on TV in a long long time.

"I'm Batman" was pure gold.
Mon Sep 08, 2008 10:38 pm UTC
Topic: 0473: "Still Raw"
Replies: 238
Views: 41737

### Re: "Still Raw" Discussion

Assuming the force of friction (of the wheel bearings not the tires on the tread mill) is 0 then it doesn't matter how fast the treadmill is moving. What you're not getting - which is really annoying because it makes the people saying it wouldn't take off go "ah-HAH! But the bearing isn't ever...
Mon Sep 08, 2008 7:48 am UTC
Topic: 0473: "Still Raw"
Replies: 238
Views: 41737

### Re: "Still Raw" Discussion

if the treadmill is moving fast enough to completely cancel the forward movement of the plane, and it can still take off, why aren't we using this technology of aircraft carriers? That's (in some sense) the point of the question: Ignoring friction in the wheels, the treadmill has no effect whatsoev...
Wed Jul 16, 2008 4:41 am UTC
Forum: Mathematics
Topic: Infinite Series, Quadratic Term in the denominator
Replies: 10
Views: 2141

### Re: Infinite Series, Quadratic Term in the denominator

By the way, I took the Ratio Test to check for convergence and it was inconclusive. I am running on the assumption that is convergent since the answer to the Euler series converged absolutely on an exact value. You can use the comparison test to see that your series converges. Each term in your ser...
Mon Jul 14, 2008 5:05 pm UTC
Forum: Food
Topic: Beer is proof that God loves us and wants us to be happy.
Replies: 1738
Views: 368236

### Re: Beer is proof that God loves us and wants us to be happy.

Imo the champagne of beers is lambic :) No, that's the fruit juice of beers. Or it's just fruit juice, I can't remember which. Lambics don't necessarily have any fruit juice in them at all. Lambic just means naturally fermented. If you can find some, I suggest you try a Gueze lambic. Its an unsweet...
Mon Jul 14, 2008 1:19 pm UTC
Forum: Movies and TV Shows
Topic: Movies that make you ignore all criticism.
Replies: 45
Views: 5848

### Re: Movies that make you ignore all criticism.

Contact. I know its cheesy as hell and gets a little preachy toward the end, but its the only movie that's ever conveyed my love for astronomy. Also, its one of the two movies that have ever made me tear up (during the scene in the spacecraft where Jody Foster's character is looking at the galaxy)....
Mon Jul 14, 2008 1:13 pm UTC
Forum: Science
Topic: Significant Figures
Replies: 13
Views: 1911

### Re: Significant Figures

Sig figs are very important in engineering. The difference between a part diameter of 1.0" and 1.00000" could add a million dollars to the cost of manufacturing the part. (values approximate) And yet engineers seem to ignore this all the time. Freaking labeling everything with a standard ...
Mon Jul 14, 2008 1:06 pm UTC
Forum: Mathematics
Topic: Mathematicians on wikipedia display liberal bias
Replies: 35
Views: 6239

### Re: Mathematicians on wikipedia display liberal bias

That rationalwiki site is just as awful (but on the opposite side), assuming most of their articles are as bad as the featured one on Peer Review ( http://rationalwiki.com/wiki/Peer_review ) and http://rationalwiki.com/wiki/Scientific_method An entire site full of Dawkinian e-atheists :((( edit: wh...
Tue Jul 01, 2008 1:11 am UTC
Forum: Science
Topic: Lathe mod
Replies: 6
Views: 1612

### Re: Lathe mod

This also greatly depends on whether you are talking about a wood lathe or a metal lathe. Generally, wood lathes are belt driven and metal lathes are gear driven. This is because you want give when working with wood and hand tools and you want rigidity when working with metal so you can get a good f...