Facts that shocked you
Discussion
ben5575 said:
GroundEffect said:
Not so much shocked me, but surprised how many people don't understand it:
People don't "float" in low earth orbit because they're too far from earth for gravity to work. It's because they're falling at the same rate as their spacecraft.
Orbital mechanics is a very curious thing.
When you say falling, do you mean falling? I thought (which means I'm highly likely to be wrong!) that it was because they were constantly accelerating as they were travelling in an orbit (velocity and all that). People don't "float" in low earth orbit because they're too far from earth for gravity to work. It's because they're falling at the same rate as their spacecraft.
Orbital mechanics is a very curious thing.
At least I knew it wasn't because there was no gravity though, so I can be cut a little bit of slack...
If you were in, for example, a lift, at a height of 400km above the earth (ISS altitude), but weren't in an orbit, you'd come back down at 1g acceleration (until terminal velocity). Whilst accelerating to terminal velocity, you would experience weightlessness since you and the lift is accelerating at the same rate. Once you reach terminal velocity, you would go back to "normal" (i.e. what you experience at rest) since you're back into an inertial reference frame - i.e. the lift has stopped
An orbit is the same as the accelerating part of the lift's fall, which is why I called it falling. It's falling sideways. Fast enough that you always miss the planet, and because of the lack of air, there's nothing to slow you down and bring you down to earth and most importantly, make you reach a terminal velocity.
GroundEffect said:
the planet, and because of the lack of air, there's nothing to slow you down and bring you down to earth and most importantly, make you reach a terminal velocity.
Lol it took me an embarrassingly long time to realise that a large part of launching something into orbit was going rapidly horizontally and not basically straight up. 
littleredrooster said:
SpudLink said:
What was the kids TV show that tried this in the '70s?
Was it Zoe's dad, Johnny? I vaguely remember it.If you could fold it 44 times, the pile would be thicker than the distance to the moon.
otolith said:
Pitre said:
I get the first one (Africa size v rest of the world) but I don't get what the Mercator one is trying to show?
When you flatten a spheroid into a map, you distort the shape and size of the shapes on it. There is more than one way of doing it (more than one projection), but whichever you choose, it's going to be wrong (because a flat plane is not a curved surface). The Mercator projection squishes stuff nearer the equator.https://www.geographyrealm.com/types-map-projectio...
thegreenhell said:
Pitre said:
I get the first one (Africa size v rest of the world) but I don't get what the Mercator one is trying to show?
It's showing the common Mercator projection with all of the countries shrinking to their real relative size rather than being distorted to fit a 2d projection system designed to make Northern hemisphere countries appear bigger than they actually are.TX.
thebraketester said:
eldar said:
P-Jay said:
Only 6 episodes of Police Squad! Shirley not.
There are 241 episodes of Paw Patrol and somehow I’ve seen them all at least 10 times.
Wait until Bluey……There are 241 episodes of Paw Patrol and somehow I’ve seen them all at least 10 times.
I might give Bluey a go
GroundEffect said:
An orbit is the same as the accelerating part of the lift's fall, which is why I called it falling. It's falling sideways. Fast enough that you always miss the planet, and because of the lack of air, there's nothing to slow you down and bring you down to earth and most importantly, make you reach a terminal velocity.
That's very interesting. I think we're both saying the same thing (possibly!). Falling sideways is the constant acceleration you have when travelling in a circle (orbit) - the old velocity vs speed thing. They're matched as you say to avoid actual falling(!) to earth, so the net effect is zero hence weightlessness. Maybe
DaveTheRave87 said:
budgie smuggler said:
Lol it took me an embarrassingly long time to realise that a large part of launching something into orbit was going rapidly horizontally and not basically straight up.
Don't worry, it took me until today.Halmyre said:
littleredrooster said:
SpudLink said:
What was the kids TV show that tried this in the '70s?
Was it Zoe's dad, Johnny? I vaguely remember it.If you could fold it 44 times, the pile would be thicker than the distance to the moon.
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