## Search found 7 matches

Tue Feb 13, 2018 4:39 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1953: "The History of Unicode"
Replies: 60
Views: 13374

### Re: 1953: "The History of Unicode"

J%r wrote:Did the image change? Somehow I only see the top rectangle.

When the cartoon was originally posted, the date on the left of the third panel was "1998" instead of "1988". I suspect correcting that was the cause of the momentary glitching.
Fri Sep 26, 2014 4:29 pm UTC
Forum: What If?
Topic: What-If 0113: "Visit Every State"
Replies: 87
Views: 33068

### Re: What-If 0113: "Visit Every State"

It's interesting to do a back of the envelope calculation for how much fuel Randall's 5-pass method would take. It looks like you could launch into a polar orbit from Cape Canaveral. (Note: Polar launches are not actually permitted from Cape Canaveral because those launch paths pass over inhabited a...
Tue Aug 20, 2013 3:22 am UTC
Forum: What If?
Topic: What-If 0058: "Orbital Speed"
Replies: 106
Views: 63133

### Re: What-If 0058: "Orbital Speed"

Yeah, even without actual friction drag from the atmospher, and even without having to increase your altitude at all, you lose energy to gravity as long as you're traveling below orbital speed at an altitude you don't want getting any lower <snip> Ah, OK thanks. Your example makes sense. It's becau...
Mon Aug 19, 2013 9:37 pm UTC
Forum: What If?
Topic: What-If 0058: "Orbital Speed"
Replies: 106
Views: 63133

### Re: What-If 0058: "Orbital Speed"

The problem is gravity drag. The longer you spend accelerating to reach your ballistic trajectory, the more time you spend fighting gravity to no benefit. I'm still not sure I understand this. Gravity is a conservative force, so you don't lose energy to heating or friction. Neglecting air resistanc...
Mon Aug 19, 2013 9:01 pm UTC
Forum: What If?
Topic: What-If 0058: "Orbital Speed"
Replies: 106
Views: 63133

### Re: What-If 0058: "Orbital Speed"

getting into an orbit (which doesn't intersect the ground) is more expensive the longer you take (and being in orbit hardly qualifies as "walking speed"...) This isn't obvious. Once you're on a ballistic trajectory, you only have so much time to get to orbital velocity before you re-enter...
Mon Aug 19, 2013 5:23 pm UTC
Forum: What If?
Topic: What-If 0058: "Orbital Speed"
Replies: 106
Views: 63133

### Re: What-If 0058: "Orbital Speed"

And when you're on an escape trajectory, your speed at periapsis will, I believe, be escape velocity - though I could be wrong, it could just be your speed at periapsis if your periapsis were at the center of gravity of the body being escaped. Escape velocity depends on altitude. (More specifically...
Sun Aug 18, 2013 7:57 pm UTC
Forum: What If?
Topic: What-If 0058: "Orbital Speed"
Replies: 106
Views: 63133

### Re: What-If 0058: "Orbital Speed"

This is one of my favorite what-if's ever, but I feel like Mr. Munroe has missed or obscured an important point: If I were at the International Space Station, orbiting at 350 km above the Earth's surface, and I was able -- using unobtanium fuel or some such -- to de-orbit a re-entry capsule by slowi...

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