What would happen if...
The earth spun so fast that the centrifugal force canceled out the gravity just enough so that everyone could jump and float in the air for extended periods of time. Then, when you jump too high, the air in the higher atmosphere that isn't spinning as fast would slow you down, and you float back down. Umm, unless it slows you down too much and gravity takes over and smashes you into the ground... loophole.
It was a fun thought.
No, wait. It wouldn't. Because the air in the lower atmosphere would be traviling faster, and should speed you up a little. Enough, you should hope at least.
It was a fun thought.
No, wait. It wouldn't. Because the air in the lower atmosphere would be traviling faster, and should speed you up a little. Enough, you should hope at least.
posted by Cyphoid at 12:08 PM
11 Comments:
Wow, I just got dizzy thinking about it. How about this? How about if you're in a helicopter and the propeller flies off and the helicopter is falling to the Earth below. When you're just about four feet from hitting bottom, you jump up. What happens?
is this under the same conditions as Drewy just described?
Hmmm... night and day would be shorter. Very interesting insight Drew.
Paperboy. If you mean you jump up inside the helicopter, then you'd hit the ceiling.
Drewster,
I expect a young geek such as yourself would have done a few calculations to consider the implications of a faster spinning earth. If you set the acceleration due to gravity equal to the centripetal acceleration, you could solve for the rotational speed of the earth that would produce the condition you described. If you were to do that, I think you would find that the earth would be spinning so fast that each day would be only 85 minutes long! Think of it Drew, if you only had 85 minutes a day to fit in eating, sleeping, personal hygiene and time on the computer, something would have to give. I’m sure your readers would be interested just which of those would be sacrificed.
But you may not even have time to think about that, because with the earth spinning so fast, the delicate balance of forces that keep our atmosphere in place would certainly be upset, and we would be left with little or no atmosphere. With no atmosphere, there would not be enough oxygen present to burn fuel to cook your dinner, and you would have to eat everything raw. That could be bad for your health Drew, had you considered that? Oh, and you wouldn’t be able to breath either.
So, now I think you would be able to consider your little scenario. If you jumped (out of breath, with no sleep, no bath, and with raw food in your belly), you would indeed get a boost from the centripetal acceleration. What would happen next is rather complicated and it would certainly depend on your how much of a push you could manage. I’m thinking you would either land a little east of your starting point or become a satellite. On balance, it doesn’t sound like that much fun.
Well, paperboy, not only does you head hit the celing of the helicopter, the celing of the helicopter hits your head, as it caves in on it.
Well thanks for running the numbers. I was going to do that, but at the time I didn't feel like it. The idea had just flung itself into my head so suddenly that I had to post it.
After 10 minutes of thought, rather than an unnoticeable gravitational force, I was thinking more of a micro gravity environment. Something where you may be able to jump 100/200 feet without much trouble. This would resolve the jumping really high and having gravity take over as speed decreases, scenario.
Having no gravity effect would result in no atmosphere, hence I like the micro gravity environment. Barometric pressure would be greatly decreased and the atmosphere would extend a great deal further out into space, but, from what I would assume, oxygen would still hold in the lower layers of the atmosphere, being the heavier gas that it is.
On the 85 minute days, I actually anticipated this as an upside. In this manner, it would be extremely easy to break up a "human day" into many "earth days". At 85 minutes a day, there turns out to be just shy of 17 of them in a 24 hour day. And, personally, I believe there should be about 5 or 6 more hours in the typical 24 hour earth day. Therefore it would be easy to tack on 4 more 85 minute earth days cycles to create a 30 hour human day. In this way, it would be a much more easier way to track time than watching the sun track across the sky and guessing on its position (which changes through the year). My opinion, of course.
And, on the helicopter, if you did not get torn apart by the rotor in the first place, then after you hit your head on the roof, you would still smash into the ground and be killed instantly.
Cyphoid,
Your original line of thought has led me to a frightening idea. For a satellite to remain in orbit, it has to meet the conditions you described, with the centripetal force balancing the gravitational force. Most of the satellites in orbit are parked in a geostationary orbit, that special orbit where a satellite can remain stationary above one point on the earth. It occurs to me that only a slight variation of the earth's rotational velocity could overcome the stabilization systems of the satellites, knocking them out of their orbits to be lost forever. Why is this scary? Well, if all of the "enemies of democracy" were to get organized enough to all run West at the same time (think hamster wheel), they could knock out our entire communications system.
I wonder if the Pentagon knows this.
That is scary, but hopefuly are spy satilites will tell us what they are doing before they do speed up the rotation of the earth.
False alarm. I just did the calculation. If you could get the world's population of 6 billion to all run West at the same time, and they all ran like Kenyan marathoners, it would take 410,000 years to change the earth's rotational speed by 1%. No wonder there's no orange alert. I don't even think Kenya's on the State Department's bad list. Nevermind.
Mmm, did I miss something Mr.C? If my line of thinking is correct, the satellites would not be lost, in a manner of speaking. If you got the earth to spin much faster and the satilites remained in their orbit, then assuming no atmospheric interfearance, the satellites would remain in their old geocentric orbit. They would no longer be geocentric for the new earth rotational speed, but they would still be in a stable orbit, and geocentric to the old earth orbit. Hence, they would not be flung out into the far reaches of the galaxy, or anything like that. They would still be orbiting the earth, albeit it would appear that the satellite is continually running in one direction at a fast pace (from a standpoint on the ground).
In order for it to be geocentric in an 85 minute day, the orbit would have to be very low. Off hand, knowing that the space shuttle makes around 90 minute orbits, iirc it would be somewhere between a 150 and a 300 mile orbit.
Yeah cyphoid, you’ve got it right. The satellites would stay in the same orbit, but it wouldn’t be geo anymore. Since those satellites can only work at geo, they would be mostly useless, or their navigation systems would try to get them back to a geo orbit. But the nav systems usually rely on things that don’t change, like star positions or the earth’s rotation. So what would really happen if the earth’s rotation changed? I think it would be satellite dependent. Some might make it and others might not. Since it generally takes so little energy to stay in a geo orbit, most would probably not have the propulsion system needed to get them to a new orbit.
Hypothetically, from a standing position on earth -- to get to a geo orbit on an earth with no atmosphere and 85 minute days – simply tuck your knees up to your belly and you’re there! You’re right about the shuttle, its about a 90 minute orbit. You really can’t get much faster than that with the atmosphere in the way!
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