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xkcd: What If? #109 - Into the Blue
Posted: Tue Sep 16, 2014 4:20 pm
by 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.
xkcd: What If? #110 - Walking New York
Posted: Tue Sep 16, 2014 4:24 pm
by bystander
Walking New York
- Could a person walk the entire city of NY in their lifetime? (including inside apartments) — Asaf Shamir
xkcd: What If? #111 - All the Money
Posted: Tue Sep 16, 2014 4:27 pm
by 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
xkcd: What If? #112 - Balloon Car
Posted: Tue Sep 23, 2014 1:25 am
by 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
Re: xkcd: What If? #112
Posted: Tue Sep 23, 2014 3:24 am
by 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.
xkcd: What If? #113 - Visit Every State
Posted: Sat Sep 27, 2014 8:15 pm
by bystander
Visit Every State
- How fast could you visit all 50 states? — as discussed by Stephen Von Worley on Data Pointed
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 3:37 am
by Beyond
so... what is the equivalent resistance between the two marked nodes, in the above xkcd?
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 4:31 am
by BDanielMayfield
Beyond wrote: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.
![Laughing :lol2:](./images/smilies/asterisk_laugh.gif)
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 5:45 am
by BMAONE23
BDanielMayfield wrote:Beyond wrote: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.
![Laughing :lol2:](./images/smilies/asterisk_laugh.gif)
http://m.wikihow.com/Calculate-Series-a ... Resistance
Here is the simple equation
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 11:03 am
by BDanielMayfield
BMAONE23 wrote:BDanielMayfield wrote:Beyond wrote: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.
![Laughing :lol2:](./images/smilies/asterisk_laugh.gif)
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 ...
![Shocked :shock:](./images/smilies/icon_eek.gif)
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 5:12 pm
by Beyond
The answer is.... stick the ends of the two leads of an Ohmmeter on the two nodes and read what the scale says.
![Laughing :lol2:](./images/smilies/asterisk_laugh.gif)
I've got the meter, but no 1-ohm resistors.
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 5:34 pm
by BDanielMayfield
Beyond wrote:The answer is.... stick the ends of the two leads of an Ohmmeter on the two nodes and read what the scale says.
![Laughing :lol2:](./images/smilies/asterisk_laugh.gif)
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 ...
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 5:41 pm
by Chris Peterson
Beyond wrote: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).
Re: xkcd: What If? #113
Posted: Mon Sep 29, 2014 8:19 pm
by Beyond
Chris Peterson wrote: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.
Re: xkcd: What If? #113
Posted: Tue Sep 30, 2014 2:44 am
by Nitpicker
Chris Peterson wrote:Beyond wrote: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
Re: xkcd: What If? #113
Posted: Tue Sep 30, 2014 3:40 am
by Chris Peterson
Actually, I didn't derive my answer. I ran a sim using a SPICE module in Matlab.
Re: xkcd: What If? #113
Posted: Tue Sep 30, 2014 3:55 am
by bystander
Application of the lattice Green's function for calculating the resistance of an infinite networks of resistors - J. Cserti
xkcd: What If? #114 - Antimatter
Posted: Fri Oct 03, 2014 10:55 pm
by bystander
Antimatter
- What if everything was antimatter, EXCEPT Earth? — Sean Gallagher
xkcd: What If? #115 - Into the Sun
Posted: Sun Oct 12, 2014 7:12 pm
by 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
xkcd: What If? #116 - No-Rules NASCAR
Posted: Fri Oct 17, 2014 2:14 pm
by 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
xkcd: What If? #117 - Distant Death
Posted: Sat Oct 25, 2014 4:06 pm
by bystander
Distant Death
- What is the farthest from Earth that any Earth thing has died? — Amy from NZ
xkcd: What If? #118 - Physical Salary
Posted: Fri Oct 31, 2014 9:12 pm
by 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
Re: xkcd: What If?
Posted: Sat Nov 01, 2014 11:35 am
by 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
xkcd: What If? #119 - Laser Umbrella
Posted: Sun Nov 16, 2014 1:36 am
by 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
Re: xkcd: What If?
Posted: Sun Nov 16, 2014 1:48 am
by geckzilla
Good to know that there are at least three livable autoclaves in Boston.