Edit: I didn’t understand how a jet engine worked, but now that I do, the question has been amended to this…
“Why does a rocket have to travel faster and faster the higher up it goes? Shouldn’t it require less and less speed as it is further from the earth it gets because there is a non-zero number(very small) of negative gravity change the higher you are?”
Edit #2: I think I suck at asking this so I’ll ask it like a 5 year old.
We have all seen videos of rockets taking off. They start very slowly, and then build in speed. Although, at first, they build up in speed. It’s not as if they torque off the earth at 20,000mph, although that would be ASTOUNDING to see. So here’s my super drawn out really dumb question that I cannot wrap my head around the answer for the life of me.
Let’s say you have a rocket going 100mph going 90 degrees straight up from the surface of the earth. Why can’t it just keep going 100mph straight up. Just keep going and going. Up, straight up. Up up up and away? Why can it move up starting from zero miles an hour? If it can move up at 5mph even for an instant, why can’t it continue at that velocity all the way up.
All the answers have been wonderful if I was asking how to get something in orbit. I’m asking why 100mph 90 degrees going straight up works down here, but not up there? I cannot find a straight answer to this question no matter what I google. I appear to be bad at research or this is just a stupid ass question. I really just don’t understand the physics of this at all.
Let’s try this another way. Say I threw a magic baseball that whatever velocity it was tossed at, it maintained until it hit a object. It doesn’t disregard gravity. It just has a magic anaerobic motor that maintains the speed. Like cruise control. Say I throw it 90 degrees straight up at 35mph. Will it leave Earth? Why or why not?
In: Engineering
To you last question yes your magic baseball will leave earth but to the commenters that are talking about orbit is important. Let me explain:
Say you had your magic baseball. Also suppose for simplicity, that no other planets or stars or things with gravity existed. Just Earth. So that baseball keeps traveling and eventually it gets to space. Yay, Space! So that is the simple answer but what if that magic force disappears? The ball will fall back down to Earth (eventually) unless it gets out of earth’s gravitational field which reaches **4,500,000,000** light years away. The Sun is, on average, **0.00001581 light years** from Earth. So that ball would have to go a distance we simply can’t imagine if it wants to stay in space.
So that begs the question: “I thought we were weightless in space? I see astronauts floating in the space station?” So what’s going on here is a key to WHY the shuttles need to accelerate. What’s actually happening here is that they are in orbit so they are impacted by gravity. They are just going so fast around earth that they are falling and “missing” the planet as they fall. Its like the weightless feeling you get at the top of a roller coaster. But because they are in orbit, they are always at the top of the roller coaster.
So that’s why they need to add speed. Not because they need it to “get” to space. Because they want to **stay** in space. Unless they go really far away (way further than the sun) they will always be impacted by gravity on Earth (and the sun, and everything else!) and eventually fall back down.
Side note: If you find this interesting there is a great video game that teaches these concepts: Kerbal Space Program
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