this post was submitted on 02 Dec 2024
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[–] [email protected] 62 points 1 day ago (6 children)

Ummm, not sure where they got these numbers from but Earth's escape velocity is not 7000mph and escaping the sun's gravitational pull (leaving the solar system from Earth) is not 30,000mph. Respectively the numbers are approximately 25,000mph and 94,000mph. You're welcome.

[–] stephen01king 1 points 7 hours ago

94000mph is relative to the sun's surface. Relative to the Earth's surface, it is around 37000mph, which means they were still wrong.

[–] [email protected] 3 points 22 hours ago (1 children)

That's 11.2 km/s and 42.1 km/s.

Also, even if the manhole cover was going at above 12 km/s the trajectory has to be right for that to result in orbit. Most paths it would take would result in it going up and then coming back down again. Similarly, if somehow it did manage more than 50 km/s and wasn't destroyed in the atmosphere, it might have the velocity to escape the sun's gravity, but probably wouldn't be on the right path to do it. Most likely it would fall into the sun.

So, assuming the 125,000 mph (55 km/s) velocity is correct, the most likely outcome is that it was a reverse-meteor, something that burned up going up through the atmosphere, not down. And even if it did have enough speed to get out of the atmosphere, and there was enough of it left, it most likely fell right back down through the atmosphere somewhere else, either burning up on re-entry or hitting the ground (or the water) somewhere else.

[–] [email protected] 2 points 14 hours ago (1 children)

Ignoring that it burned up and ignoring losses due to drag if it somehow didn't. Isn't the point of escape velocity that it explicitly won't come back down.iar least not on earth. Your trajectory won't matter as you have enough velocity to escape the gravity of earth and will orbit the sun. Further if you managed the solar system escape velocity you will end up orbiting the galactic core. Trajectory doesn't matter if you have escape velocity. Correct trajectory just minimizes the delta v needed to reach that escape velocity.

At least that's all my recollection.

[–] [email protected] 1 points 12 hours ago

Escape velocity means you could stay in orbit. It doesn't guarantee anything if you launch at the wrong angle.

[–] [email protected] 23 points 1 day ago

Gotta love Tumblr. Just massive amounts of disinformation and bullshit all the time.

[–] [email protected] 16 points 1 day ago

Also it would have atomized.

[–] [email protected] 2 points 1 day ago (1 children)

I like how they are implying the speed of light is only 500000mph (as opposed to 671,000,000 mph or 1,080,000,000kph)

[–] [email protected] 1 points 1 day ago (1 children)
[–] [email protected] 1 points 1 hour ago

Ah sorry, I should have specified that the post not only got the escape velocity wrong as you pointed out they also got the speed of light wrong near the end.

[–] [email protected] 4 points 1 day ago (1 children)

yeah, and it is not "research" to check it. They literally teach it in primary school physics.

[–] [email protected] 15 points 1 day ago (1 children)
[–] [email protected] 5 points 1 day ago

I mean, what for? Knowing that number isn't a life skill.