## Search found 14 matches

Mon Apr 29, 2013 1:26 pm UTC
Topic: 1205: "Is It Worth the Time?"
Replies: 76
Views: 27246

### Re: 1205: "Is It Worth the Time?"

This immediately reminded me of xkcd.com/974/
Mon Mar 18, 2013 5:24 pm UTC
Topic: 1187: "Aspect Ratio"
Replies: 92
Views: 21339

### Re: 1187: "Aspect Ratio"

What's worse than the linear stretch of 4:3 to 16:9, is the variable stretch sometimes called "panorama mode" where the sides are stretched and the center stays proportional. This mode has good intentions, but wait until someone or something moves across the screen, accelerating and decele...
Wed Oct 10, 2012 12:10 pm UTC
Topic: 1119: "Undoing"
Replies: 121
Views: 24253

### Re: 1119: "Undoing"

Shouldn't this be a "What-if"? I've always wondered about the effect of wind turbines on the wind. This comic suggests there is less wind, um, downwind of the turbine. Sure, not as much less as is suggested here, but doesn't a huge wind farm have a measurable effect? Wouldn't the same thi...
Tue Sep 18, 2012 12:55 pm UTC
Forum: What If?
Topic: What-If 0012: "Raindrop"
Replies: 91
Views: 25830

### Re: What-if 0012: Raindrop

I calculated the terminal velocity of such a raindrop as 4490 m/s, which is 10,000 mph or mach 13.5. In a vacuum, it would take 7.6 minutes of falling to reach this speed, but in air it would be slower and would approach terminal velocity asymptotically. I got the equation from Wikipedia: t.v. = sqr...
Wed Sep 12, 2012 8:52 pm UTC
Forum: What If?
Topic: What-If 0011: "Droppings"
Replies: 68
Views: 32117

### Re: What-If 0011: Droppings

Although the starting and ending units are in mass of something, that something matters. Perhaps you're right. Do you agree, though, that there is meaning in the tube model of fuel efficiency? In the tube of fuel, miles traveled is the same thing as miles of gasoline, so canceling should be just fi...
Wed Sep 12, 2012 5:38 pm UTC
Forum: What If?
Topic: What-If 0011: "Droppings"
Replies: 68
Views: 32117

### Re: What-If 0011: Droppings

Surprised at his bit about unit conversions. Mostly because it's factually incorrect, and I tend to like him for being right on these things. :( "miles per gallon" is lazy notation we accept in speech. If you want to use it in math, you need to recognize it's "miles traveled per gall...
Tue Sep 11, 2012 8:57 pm UTC
Forum: What If?
Topic: What-If 0011: "Droppings"
Replies: 68
Views: 32117

### Re: What-If 0011: Droppings

I wanted to offer my take on the fuel economy units. The best form to use depends on what you're most interested; in other words, what is fixed and what is variable. In the beginning, people were more concerned about distance . For a given fill-up, how much distance do I get? A car that could get 20...
Tue Sep 11, 2012 8:55 pm UTC
Forum: What If?
Topic: What-If 0011: "Droppings"
Replies: 68
Views: 32117

### Re: What-If 0011: Droppings

> If you took all the gas you burned on a trip and stretched it out into a thin tube along > your route, 0.1 square millimeters would be the cross-sectional area of that tube. It seems to me that is rather close to the cross section of the fuel line actually going from the tank to the engine. Anybo...
Tue Sep 11, 2012 3:20 pm UTC
Forum: What If?
Topic: What-If 0011: "Droppings"
Replies: 68
Views: 32117

### Re: What-If 0011: Droppings

What comes out is, in the case of gasoline, (720 (kg/L)/1.98 (kg/L)^(2/3)*(32+12)u/12u*0.335 mm^2=62 mm^2 of CO2, neglecting the mass contribution of non-carbon atoms in petroleum, and assuming perfect combustion. So really more something like 60 mm^2 of CO2. Imagining a tube of CO 2 around a centi...
Tue Sep 11, 2012 2:08 pm UTC
Forum: What If?
Topic: What-If 0011: "Droppings"
Replies: 68
Views: 32117

### Re: What-If 0011: Droppings

Something doesn't smell right about that last formula. Suppose we double the number of miles driven, to 6 trillion a year. The amount of guano is constant, so one would expect that the efficiency needed in miles per gallon to increase, but if we put it into the formula, we find that it decreases. Y...
Mon Sep 10, 2012 12:08 pm UTC
Replies: 121
Views: 31353

This reminds me of the GTD method by David Allen. Unless you come up with a good system for tying those balloons down until you can deal with them, you'll never be able to fully control the one you're holding now.
Wed Jul 18, 2012 1:01 pm UTC
Forum: What If?
Topic: What-If 0003: "Yoda"
Replies: 122
Views: 82009

### Re: What-If 0003: Yoda

Also I have seen a big mistake in your calculation: 5300 * 0.9 * 1.4 / 3.6 = 1855 W = 1.85 kW (NOT 18.5) You forgot to include "g", which is 9.81 m/s^2. So 5300 * 0.9 * 9.81 * 1.4 / 3.6 = 18197 W = 18.2 kW. Although he uses 18.3 for some reason. It's confusing because the "g" in...
Tue Apr 10, 2012 4:43 pm UTC
Topic: 1040: "Lakes and Oceans"
Replies: 166
Views: 81547

### Re: 1040: "Lakes and Oceans"

sorry, but i'm gonna do it... i require clarifaction on 'bike tyre'... Road Bike [100psi]? cross country [~45 PSI]? trail bike [~20 PSI]? :) But a great cartoon, I love the scale chart ones... #hopes for poster# Has to be the road bike tire at a pressure of perhaps 110 psi (7 atms). It's too deep t...
Tue Apr 10, 2012 1:04 pm UTC