xkcd: What If?

[bystander]

Into the Blue

• If I shot an infinitely strong laser beam into the sky
  at a random point, how much damage would it do? — Garrett D.

[bystander]

Walking New York

• Could a person walk the entire city of NY in their lifetime? (including inside apartments) — Asaf Shamir

[bystander]

All the Money

• People sometimes say "If I had all the money in the world ..." in order to
  discuss what they would do if they had no financial constraints. I'm curious,
  though, what would happen if one person had all of the world's money? — Daniel Pino

[bystander]

Balloon Car

• My 12-year-old daughter is proposing an interesting project. She is planning to attach a number
  of helium balloons to a chair, which in turn would be tethered by means of a rope to a Ferrari.
  Her 13-year-old friend would then drive the Ferrari around, while she sits in the chair enjoying
  uninterrupted views of the countryside. Leaving aside the legal and insurance difficulties, my
  daughter is keen to know the maximum speed that she could expect to attain, and how many
  helium balloons would be required. — Phil Rodgers, Cambridge, UK

[geckzilla]

Two thoughts: First, seems like a novel way to kill someone by tying them to a balloon and having them freeze to death high in the atmosphere. Second, seems like a novel way to steal a Ferrari.

[bystander]

Visit Every State

• How fast could you visit all 50 states? — as discussed by Stephen Von Worley on Data Pointed

[Beyond]

so... what is the equivalent resistance between the two marked nodes, in the above xkcd?

[BDanielMayfield]

so... what is the equivalent resistance between the two marked nodes, in the above xkcd?

My quick guess would be 1 ohm. Prove me wrong, I dare ya.

[BMAONE23]

so... what is the equivalent resistance between the two marked nodes, in the above xkcd?

My quick guess would be 1 ohm. Prove me wrong, I dare ya.

http://m.wikihow.com/Calculate-Series-a ... Resistance
Here is the simple equation

[BDanielMayfield]

so... what is the equivalent resistance between the two marked nodes, in the above xkcd?

My quick guess would be 1 ohm. Prove me wrong, I dare ya.

http://m.wikihow.com/Calculate-Series-a ... Resistance
Here is the simple equation

Yes, the basic equations are quite simple, but it's a deceptively complex network. I didn't want to get stuck in the road ...

[Beyond]

The answer is.... stick the ends of the two leads of an Ohmmeter on the two nodes and read what the scale says. I've got the meter, but no 1-ohm resistors.

[BDanielMayfield]

The answer is.... stick the ends of the two leads of an Ohmmeter on the two nodes and read what the scale says. I've got the meter, but no 1-ohm resistors.

I thought of that too, but the problem is that you'd need an infinite number of resistors ...

[Chris Peterson]

so... what is the equivalent resistance between the two marked nodes, in the above xkcd?

These resistor network problems are routinely assigned in first year college electronics class.

In this case, the answer is about 0.77 ohms (in fact, it's exactly 4/pi - 0.5).

[Beyond]

These resistor network problems are routinely assigned in first year college electronics class.

But not in Technical School electrical shop classes, at least not the ones i was in w-a-y back in the 60's.

[Nitpicker]

so... what is the equivalent resistance between the two marked nodes, in the above xkcd?

These resistor network problems are routinely assigned in first year college electronics class.

In this case, the answer is about 0.77 ohms (in fact, it's exactly 4/pi - 0.5).

In my classes, we failed if we gave the correct answer with no derivation:
http://www.mathpages.com/home/kmath668/kmath668.htm

[Chris Peterson]

In my classes, we failed if we gave the correct answer with no derivation:
http://www.mathpages.com/home/kmath668/kmath668.htm

Actually, I didn't derive my answer. I ran a sim using a SPICE module in Matlab.

[bystander]

Application of the lattice Green's function for calculating the resistance of an infinite networks of resistors - J. Cserti

• arXiv.org > cond-mat > arXiv:cond-mat/9909120 > 08 Sep 1999 (v1), 12 Jan 2000 (v4)

[bystander]

Antimatter

• What if everything was antimatter, EXCEPT Earth? — Sean Gallagher

[bystander]

Into the Sun

• When I was about 8 years old, shoveling snow on a freezing day in Colorado, I wished
  that I could be instantly transported to the surface of the Sun, just for a nanosecond,
  then instantly transported back. I figured this would be long enough to warm me up
  but not long enough to harm me. What would actually happen? — AJ, Kansas City

[bystander]

No-Rules NASCAR

• If you stripped away all the rules of car racing and had a contest which was
  simply to get a human being around a track 200 times as fast as possible,
  what strategy would win? Let's say the racer has to survive. — Hunter Freyer

[bystander]

Distant Death

• What is the farthest from Earth that any Earth thing has died? — Amy from NZ

[bystander]

Physical Salary

• What if people's incomes appeared around them as cash in real time?
  How much would you need to make to be in real trouble? — Julia Anderson, Albuquerque, NM

[MargaritaMc]

Thanks for posting these, bystander! I always enjoy them but don't remember to go to the website if you don't post the links here.
M

[bystander]

Laser Umbrella

• Stopping rain from falling on something with an umbrella or a tent is boring. What
  if you tried to stop rain with a laser that targeted and vaporized each incoming
  droplet before it could come within ten feet of the ground? — Zach Wheeler

[geckzilla]

Good to know that there are at least three livable autoclaves in Boston.