## Search found 139 matches

- Fri Apr 07, 2017 9:02 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1821: "Incinerator"
- Replies:
**25** - Views:
**6765**

### Re: 1821: "Incinerator"

How would you dispose of the word's biggest trash can?

- Fri Sep 14, 2012 1:44 am UTC
- Forum: What If?
- Topic: What-If 0011: "Droppings"
- Replies:
**68** - Views:
**31135**

### Re: What-If 0011: Droppings

Once I was lying on my back on the lawn and a hummingbird peed/pood in my eye. It was flying by 15 or 20 feet above me and I clearly saw, and then felt, a small single drop of ick fall from it to me.

- Thu Jun 07, 2012 6:45 pm UTC
- Forum: Mathematics
- Topic: Stumped on this problem: probably calculus
- Replies:
**7** - Views:
**1646**

### Re: Stumped on this problem: probably calculus

Once I had the solution from Qaanol it led me to a more simple solution that does not require calculus: in this problem the stirring does not matter at all. The average age of the exiting water must be [size of chamber] / [flow rate], giving 1 for the original problem.

- Thu Jun 07, 2012 4:26 am UTC
- Forum: Mathematics
- Topic: Stumped on this problem: probably calculus
- Replies:
**7** - Views:
**1646**

### Re: Stumped on this problem: probably calculus

Great explanation, thank you.

- Thu Jun 07, 2012 2:46 am UTC
- Forum: Mathematics
- Topic: Stumped on this problem: probably calculus
- Replies:
**7** - Views:
**1646**

### Re: Stumped on this problem: probably calculus

Qaanol wrote:Your scenario yields a differential representation as A′=1-bA. Do you see why?

Nope.

I understand the equation and can solve from here, but I do not see how this equation comes from the problem.

- Thu Jun 07, 2012 1:02 am UTC
- Forum: Mathematics
- Topic: Stumped on this problem: probably calculus
- Replies:
**7** - Views:
**1646**

### Stumped on this problem: probably calculus

I came up with this idea while attempting to devise devious bonus problems for students, but have not yet been able to solve. A 1 liter tank has a an intake pipe and an output pipe. The tank is initially full. Beginning at t = 0, water flows in to the tank through the intake at 1 liter per hour and ...

- Wed May 16, 2012 4:18 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1056: "Felidae"
- Replies:
**170** - Views:
**45056**

### Re: 1056: Felidae

OS Maru.

- Wed Nov 09, 2011 6:43 pm UTC
- Forum: Mathematics
- Topic: Conditional Probability Question
- Replies:
**16** - Views:
**4073**

### Re: Conditional Probability Question

First, it is not ok that this irresponsible pet owner has p=.4 for not feeding their dog. Second, Also, to make it more intuitive / easier to visualize, you may want to imagine that instead of 1 dog, you have a large number of (say 1000) identical dogs. This is a very, very fun thing to imagine. Don...

- Thu Oct 13, 2011 2:52 am UTC
- Forum: Mathematics
- Topic: Your favorite "tricky" integrals?
- Replies:
**46** - Views:
**14283**

- Sat Oct 01, 2011 11:00 pm UTC
- Forum: Mathematics
- Topic: vote counting probability puzzle
- Replies:
**2** - Views:
**757**

- Sat Oct 01, 2011 8:58 pm UTC
- Forum: Mathematics
- Topic: vote counting probability puzzle
- Replies:
**2** - Views:
**757**

### vote counting probability puzzle

A co-worker brought this one in, from an older collection in a book of puzzles. Alice and Bob (and no other candidates) ran for mayor. Alice won the election with 300 votes, to Bob's 200. The votes were counted one at a time, in random order. As each vote was counted the totals so far were announced...

- Wed Aug 10, 2011 5:45 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0936: "Password Strength"
- Replies:
**893** - Views:
**314392**

### Re: 0936: "Password Strength"

I'll share a system I read about to create multiple easy to remember and hard to bruteforce passwords for different sites 1) make an anagram from a memorable phrase, with number/symbol substitution and/or capitalization (6-8 characters) Bugs Bunny gives me funny feelings = bbgmff = 88gmFF 2) for eac...

- Wed Mar 30, 2011 4:02 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0879: "Lamp"
- Replies:
**151** - Views:
**36134**

### Re: 0879: "Lamp"

your wish is my come, man.

- Thu Jan 06, 2011 7:36 pm UTC
- Forum: Mathematics
- Topic: AP Calc: Are there practice tests with 2011 rule changes?
- Replies:
**1** - Views:
**515**

### Re: AP Calc: Are there practice tests with 2011 rule changes

I'll answer my own question: I got the info from another forum but I'll share it here:

http://apcentral.collegeboard.com/apc/p ... 12187.html

This page has updates to old (for sale) practice exams with scoring keys under the new system.

http://apcentral.collegeboard.com/apc/p ... 12187.html

This page has updates to old (for sale) practice exams with scoring keys under the new system.

- Thu Jan 06, 2011 4:44 pm UTC
- Forum: Mathematics
- Topic: AP Calc: Are there practice tests with 2011 rule changes?
- Replies:
**1** - Views:
**515**

### AP Calc: Are there practice tests with 2011 rule changes?

The AP Calculus exam will have 2 rule changes for the 2011 test dates: There is no longer a penalty for incorrect multiple choice answers (instead the thresholds for earning a 2/3/4/5 will be higher) There will be 4 free response questions with calculator use allowed and 2 without (used to be 3 of e...

- Fri Dec 31, 2010 6:12 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0841: "Audiophiles"
- Replies:
**266** - Views:
**50888**

- Fri Dec 10, 2010 6:07 am UTC
- Forum: General
- Topic: Logical fallacies/douchebaggery in commercials.
- Replies:
**4973** - Views:
**745841**

### Re: Logical fallacies/douchebaggery in commercials.

I am confused by commercials for televisions that show you how good the picture on the television looks.

Let's get that tv, the picture looks way better than ours does! o wait...

- Thu Oct 07, 2010 8:43 pm UTC
- Forum: Mathematics
- Topic: Order of operations for trig, logarithms
- Replies:
**11** - Views:
**5274**

### Re: Order of operations for trig, logarithms

mike-l wrote:No, it shows that the multiplication is applied first.

Shamed. I'll refrain from destroying the evidence of my blunder by edit, it would cause subsequent posts to no longer make sense.

pemdTLas

- Thu Oct 07, 2010 8:26 pm UTC
- Forum: Mathematics
- Topic: Order of operations for trig, logarithms
- Replies:
**11** - Views:
**5274**

### Order of operations for trig, logarithms

grade schoolers learn PEMDAS as an acronym for order of operations (parentheses, exponents, multiply and divide, add and subtract), but this doesn't tell what order to read expressions involving trig or logarithm In general, from my experience sin x^2 is read as sin (x^2) , not (sinx)...

- Thu Sep 23, 2010 6:21 pm UTC
- Forum: Mathematics
- Topic: r = theta, convert to rectangular coordinates?
- Replies:
**11** - Views:
**11302**

### Re: r = theta, convert to rectangular coordinates?

Well, look at the graph. For any x there are an infinite number of y that satisfy it. You're not going to turn it into a function without specifying half of a single arc, and I can't imagine that would be very valuable. That's exactly what we're looking for, actually. Can a given section of the spi...

- Thu Sep 23, 2010 5:58 pm UTC
- Forum: Mathematics
- Topic: r = theta, convert to rectangular coordinates?
- Replies:
**11** - Views:
**11302**

### Re: r = theta, convert to rectangular coordinates?

You'll end up with something genuinely hideous, and that's okay. I'm fine with hideous, but I cannot get to a function of y strictly in terms of x. There's always an r or theta left that I cannot substitute out. or directly, root(x^2 + y^2) = arcsin (y/r) for positive x so root(x^2 + y^2) = arcsin ...

- Thu Sep 23, 2010 4:56 pm UTC
- Forum: Mathematics
- Topic: r = theta, convert to rectangular coordinates?
- Replies:
**11** - Views:
**11302**

### r = theta, convert to rectangular coordinates?

Express r = theta in rectangular coordinates.

It's not my homework, but it's a problem in the 'precalculus-review' section of a mainstream calculus textbook (Larson, section 10.4, #39).

My normal approach is useless here.

It's not my homework, but it's a problem in the 'precalculus-review' section of a mainstream calculus textbook (Larson, section 10.4, #39).

My normal approach is useless here.

- Wed Aug 25, 2010 4:01 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0784: "Falling Asleep"
- Replies:
**96** - Views:
**28481**

- Fri Apr 16, 2010 4:07 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0728: "iPad"
- Replies:
**63** - Views:
**15473**

### Re: "iPad" discussion

There are, right now, monkeys controlling robotic arms via neural implants.

Pics or it didn't happen.

- Tue Nov 17, 2009 9:29 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0663: "Sagan-Man"
- Replies:
**107** - Views:
**23437**

- Tue Oct 27, 2009 9:51 pm UTC
- Forum: Science
- Topic: reinventing the wheel (or watch)
- Replies:
**44** - Views:
**5301**

### Re: reinventing the wheel (or watch)

gmalivuk wrote:oblivimous wrote:Iron, Silicon, Uranium, etc. are all as easy to acquire on this island as they are at their most accessible locations elsewhere on earth.

Now or when those things first began to be used?

When those things first began to be used.

- Tue Oct 27, 2009 5:34 pm UTC
- Forum: Science
- Topic: reinventing the wheel (or watch)
- Replies:
**44** - Views:
**5301**

### reinventing the wheel (or watch)

A team of ten people are chosen from among the best minds of modern science and engineering to work on a unique project, with a preference for people who also have relevant practical skills in areas such as mining, metallurgy, blacksmithing, etc. These people are placed on a deserted island with no ...

- Fri Oct 16, 2009 7:26 pm UTC
- Forum: School
- Topic: High School Pranks
- Replies:
**684** - Views:
**88750**

### Re: High School Pranks

Amishdemon wrote:My brother wanted to fill water balloons with paint and the put them in the hallway and see what happens.

JELL-O. Fill them with Jell-O

1) Make Jello

2) In liquid form, pour into balloons. From a 2-liter bottle.

3) Balloons in fridge.

- Fri Oct 09, 2009 5:36 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0647: "Scary"
- Replies:
**271** - Views:
**57619**

### Re: "Scary" Discussion

America is less than three lifetimes old. If I was born in 1825-1845 and lived to 100, then in my childhood I met elders who remembered the revolution and in my old age I met children who still live. Regarding Mother Jones, Utah Phillis said: "It is hard for the mind to encompass the life that ...

- Sun Jul 12, 2009 4:26 pm UTC
- Forum: Mathematics
- Topic: Post your interesting/challenging/fun integrals
- Replies:
**53** - Views:
**9532**

### Post your interesting/challenging/fun integrals

For many students, integration is an exciting topic because, especially at first, every problem is a puzzle. After years of doing mathematics where textbook-drill-problems can be solved by rote, suddenly problems require varying degrees of cleverness. Let's collect the best here. Problems should be ...

- Sun Jul 12, 2009 4:04 pm UTC
- Forum: Mathematics
- Topic: Boundary Optimization
- Replies:
**16** - Views:
**1314**

### Re: Boundary Optimization

If you count overlaps, then my first thought would be to run a circle N m in circumference, so if you lose all your energy, you've maximised the area. Then I'd repeat this with what energy is left, and repeat this with what energy is left.... and so on. If by "overlaps" you mean winning m...

- Sat Jul 11, 2009 11:40 pm UTC
- Forum: Mathematics
- Topic: Boundary Optimization
- Replies:
**16** - Views:
**1314**

### Boundary Optimization

There’s an old story about a man who is told that he will be given ownership of whatever section of land he can run the perimeter of in one day. He gets greedy and pushes his physical limits, but just makes it back to the starting point at the deadline. Then he drops dead from exhaustion. There’s pr...

- Wed Jun 24, 2009 12:34 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0600: "Android Boyfriend"
- Replies:
**136** - Views:
**43135**

### Re: "Android Boyfriend" Discussion

It's not ok that the sound effects remind me of this

- Tue Jun 16, 2009 4:36 pm UTC
- Forum: Music
- Topic: Most ridiculous music myth you ever heard
- Replies:
**46** - Views:
**4894**

### Re: Most ridiculous music myth you ever heard

George Clinton has a BA in mathematics.

- Tue Jun 16, 2009 4:36 pm UTC
- Forum: Music
- Topic: Headphones that can take wear-and-tear.
- Replies:
**18** - Views:
**2733**

### Re: Headphones that can take wear-and-tear.

Senn's are good, but you can't beat the Grado 60's for sound quality or durability. They're $80 new, not too hard to find used. Only negative, they use a 1/4" jack, so you'll need an adapter, and they have a cord about twice as long as it should be (which is a bonus if you ever want to plug int...

- Fri Jun 05, 2009 3:17 pm UTC
- Forum: Mathematics
- Topic: Why does the letter "b" represent the y-intercept?
- Replies:
**23** - Views:
**5758**

### Re: Why does the letter "b" represent the y-intercept?

Sir_Elderberry wrote:Considering how they teach quadratics, y = ax + b makes much more sense.

Considering how they teach quadratics, y = bx + c would make the most sense, and, afaik, nobody uses that form.

- Sun Apr 05, 2009 6:38 am UTC
- Forum: General
- Topic: Uh-oh. It's a Youtube party and you're up next. What do you show 'em?
- Replies:
**2143** - Views:
**722184**

### The worst thing on youtube

I nominate http://www.youtube.com/watch?v=ZGUYEmTP ... re=related

You'll never watch Karate Kid II the same way again.

Got worse?

Edit: edited.

You'll never watch Karate Kid II the same way again.

Got worse?

Edit: edited.

- Wed Mar 04, 2009 5:34 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0551: "Etch-a-Sketch"
- Replies:
**124** - Views:
**25332**

### Re: "Etch-a-Sketch" Discussion

There's a guy in the niegborhood who is a genius with the sketch. Here's some of his work. His site is http://www.michaelmcnevin.com/ http://www.michaelmcnevin.com/images/etchasketchofbagger.jpg http://images.tribe.net/tribe/upload/photo/727/3ba/7273ba02-b894-4da1-8fe7-ce1e10a41d11.large-profile.jpg

- Fri Jan 30, 2009 10:52 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0537: "Ducklings"
- Replies:
**150** - Views:
**45924**

### Re: "Ducklings" Discussion

dennisw wrote:

There are six flavors of quacks: Up, Down, Top, Bottom, Strange, Charm

I thought all quacks were down.

- Fri Jan 30, 2009 9:46 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0537: "Ducklings"
- Replies:
**150** - Views:
**45924**

### Re: "Ducklings" Discussion

Two issues here require investigation: one: We need to know what rule traveling duckling follow. If each duckling moves by following the trail of the preceding duckling, then we create a stable duckloop. But if each duckling moves by heading directly toward the preceding duckling, then, as we recall...