Explaining to flat-earthers why space rockets launch in an arc

Flat-earthers tend to have very childish notions about pretty much everything, and how space rockets work is no exception. A 10-year-old child often wonders why space rockets don't go straight up rather than making a curve that ends up with the rocket flying almost horizontally. Wouldn't it be easier to just go straight up?

And, of course, flat-earthers can't understand it either because they are at the same intellectual level.

Well, I'll try to explain it as simply as possible:

Space rockets, even those that end up launching probes or space capsules away from Earth, need to get into low-Earth orbit first.

Why? Because getting to space requires an absolutely humongous amount of fuel, and the main rocket booster (the biggest cylinder) and the auxiliary boosters (the slightly smaller cylinders on the sides) have only a limited amount of fuel in order to get to space before running out of fuel.

In other words, the big rocket booster does not have enough fuel to go on forever. It only has a limited amount of fuel, only enough to get to low-Earth orbit.

If the rocket went straight up then yes, it could get a bit farther than if flying in the arc, but after it runs out of fuel the rocket would just slow down and start falling back to Earth. No different than if you throw a rock directly up, and then it slows down and falls back. The rocket would do the same, just going to a much higher altitude.

So what's the solution to this problem? How to remain in space even after the main rocket booster runs out of fuel?

The solution is to get into low-Earth orbit instead.

Being in orbit means that the satellite or spacecraft is moving sideways at such a huge speed that it matches the falling rate, which makes it orbit around the Earth in an almost circular path. That way it can remain there without any propulsion.

So the main role of the primary and secondary rocket boosters is to get up there and cause a sideways motion so fast that it achieves a stable orbit. That's why it ascends in an arc that ends up being almost horizontal.

So what happens after it has reached orbit? How does it get any further?

The probe or spacecraft detaches from the main rocket boosters, and has its own smaller rockets that are now used to maneuver it further. Up there, in orbit, in a weightless state and without air resistance, significantly less fuel is needed to maneuver and get into higher orbits and even out of Earth's influence. In addition, gravitational slingshots using the Earth itself are used to help this.

Orbital mechanics are a complicated subject, but the primary point of this post is to explain why space rockets launch in an arc rather than straight up.