41–50 of 72 posts
> There's one more problem: The Moon doesn't always stay the same distance from Earth. Its orbit takes it closer and farther away. Then use a pole that is strong enough to eliminate this problem.
Earlier quoted context omitted.
Let me guess - your favorite map projection is Goode Homolosine. You like easy solutions. You think we wouldn't have so many problems if we'd just elect normal people to Congress instead of Politicians. You think airlines should just buy food from the restaurants near the gates and serve that on board. You change your car's oil, but secretly wonder if you really need to.
For reference: https://www.xkcd.com/977/
Earlier quoted context omitted.
Let me guess - your favorite map projection is Goode Homolosine. You like easy solutions. You think we wouldn't have so many problems if we'd just elect normal people to Congress instead of Politicians. You think airlines should just buy food from the restaurants near the gates and serve that on board. You change your car's oil, but secretly wonder if you really need to.
For reference: https://www.xkcd.com/977/
Earlier quoted context omitted.
> Actually, the person sliding the pole would be like an object changing orbit. Remember, Moon orbits Earth. Even at L1 you can't just push yourself and coast along the pole. The movement along the pole is changing orbits and as we know this requires energy. In this case if you push yourself along the pole you would suddenly find yourself drifting away from it. Suppose you tether yourself to the pole with a ring, and…
The mentioned loop around the pole attached to your waist would do but since none of the extremely detailed drawings contained the loop we must assume that the person travaled the pole without the loop. Moon orbits Earth at about 1km/s and you have to loose orbital speed as you move along the pole. Since the pole distance is about 400000km and the orbital speed to loose is 1km/s it means you need to loose about 2.5mm…
> Note: While you're flinging yourself along, be careful not to drift out of reach of the pole. Hopefully you brought some kind of safety line so you can recover if that happens.
Of course you have lateral forces on the pole, that's not in question. But if you're sliding down the pole then you're, you know, sliding down the pole. That means you are hanging on to it somehow, or tethered to it, or something.
The point is that if you are actually sliding down the pole then it really does actually work.
> ... you would be surprised to find yourself travelling away from the pole at 2.5mm/s after 1km.
No, I wouldn't be surprised at all, because I do know a little about orbital mechanics. Possibly not as much as you do, but I do give talks on it, so if you can explain clearly how sliding down a pole (once closer than L1) won't work, I'd be really interested to hear it, because so far what you're saying hasn't convinced me.
If all you're doing is saying "If you're not tethered to the pole then you'll drift away from it and it won't work." then we have no problem. But I'm considering the case where we are, in fact, sliding down the pole.
I would imagine that what the five year old who asked wanted was an intuitive sense of how far away the moon is. My answer would have been far less interesting. I would assume a reasonable rate at which a child slides down a pole, say 1 meter per second, multiplied by roughly 384,000km from the moon to Earth, and it would take a little over 12 years.
The whole book is about, as the subtitle states "Serious Scientific Answers to Absurd Hypothetical Questions". (Sorry for saying the (possibly) obvious.) And this is what makes it wonderful.
Earlier quoted context omitted.
> Actually, the person sliding the pole would be like an object changing orbit. Remember, Moon orbits Earth. Even at L1 you can't just push yourself and coast along the pole. The movement along the pole is changing orbits and as we know this requires energy. In this case if you push yourself along the pole you would suddenly find yourself drifting away from it. Suppose you tether yourself to the pole with a ring, and…
The mentioned loop around the pole attached to your waist would do but since none of the extremely detailed drawings contained the loop we must assume that the person travaled the pole without the loop. Moon orbits Earth at about 1km/s and you have to loose orbital speed as you move along the pole. Since the pole distance is about 400000km and the orbital speed to loose is 1km/s it means you need to loose about 2.5mm…
Earlier quoted context omitted.
The mentioned loop around the pole attached to your waist would do but since none of the extremely detailed drawings contained the loop we must assume that the person travaled the pole without the loop. Moon orbits Earth at about 1km/s and you have to loose orbital speed as you move along the pole. Since the pole distance is about 400000km and the orbital speed to loose is 1km/s it means you need to loose about 2.5mm…
Quoting: > Note: While you're flinging yourself along, be careful not to drift out of reach of the pole. Hopefully you brought some kind of safety line so you can recover if that happens. Of course you have lateral forces on the pole, that's not in question. But if you're sliding down the pole then you're, you know, sliding down the pole. That means you are hanging on to it somehow, or tethered to it, or something. T…
Of course, if you decide to actually fall to Earth from L1 that starts becoming problem. I'm too lazy to calculate exact terminal velocity you would reach when falling L1 to Earth (it won't be the 11km/s you would reach if you were falling from Moon orbit because you also have Moon tugging you). I estimate it not lower than 9km/s (Moon has 2.4km/s escape velocity).
Now, if you moved along the pole at 9km/s you would feel much more tug (noticable 2.5cm/s2) or about 1/40th of Earth surface gravity. If you were 80kg person that would mean about 2kg apparent force.
Of course, by that time you wouldn't be thinking much about it as you would have other problems in mind...
> There's one more problem: The Moon doesn't always stay the same distance from Earth. Its orbit takes it closer and farther away. Then use a pole that is strong enough to eliminate this problem.
Reading these makes me very happy, I'm so grateful Mr Munroe is still working on them.
Do you know of any similar websites? I have a couple of questions that I would like to see answered. I emailed mr Munroe in the past but he never replied, I'm sure he has thousands of questions from readers to choose from.