eli5 earth escape speed

Question

can someon eexplain to me how this escape speed of roughly 40.000km/h works? , do i need this only at the start or at the end of escaping the earth,? cant i just leave it with lets say 3km/h. im totally lost pls help

In: Physics

Answer 1

If you were moving at 3 km/h, you would come back down to the ground. You move 3 km/h every day.

Orbit is all about going so fast that you fall but constantly miss the ground. Without atmosphere, such as on the moon, you only need to be as high as the highest elevation. So this can be achieved 1 foot from the ground (assuming there is no mountains in your way of course).

From there you can add speed at different parts of your orbit to affect your orbital path at the opposite end. If you have an orbit that is an oval that passes close by the Earth and then goes way out away from it, you move fastest when closest to the Earth. And slowest at the furthest point away.

Basically as you move away, gravity pulls you back. Slowing you down until you turn around and proceed back down your orbit towards Earth.

You need to have enough speed to get past the point where gravity is able to pull you back. At which time you will begin orbitting the sun, which has another escape speed you need to reach to leave it’s orbit.

In space, you are always orbitting something. You need to achieve minimum orbital speed to avoid hitting the ground. And to leave your gravitational body and enter the next, you need to go fast enough to escape that bodies gravity (the sphere of influence).

Technically you dont need to orbit. You can go to space without orbitting. You will come straight back down again. If you went fast enough you could reach escape velocity this way. However it would be INCREDIBLY inefficient as you would be fighting gravity directly the entire time flying straight up. This is why rockets pitch over so soon. Due to the atnosphere, they need to get high enough to avoid getting slowed down. But they are able to get more bang for their buck fuel wise by going sideways rather than straight upwards for long.