I’ve never really understood the physics of this. Obviously it works somehow — I’m not a moonlanding denier or anything — but my (admittedly primitive) brain continues to insist that a rocket thruster needs something to push *against* in order to work.
So what is it pushing against if space is essentially a void?
In: 7157
They’re pushing against the rocket. Remember Newton’s 3rd Law of Motion: every action has an equal and opposite reaction. If you throw stuff out the back of the rocket, it pushes the rocket forward. That’s what a rocket does: it pushes some stuff very quickly out the back of the rocket.
Cool concept: Start with a stationary rocket and fire its engine so it’s moving. Then back way up and look at the whole system of the rocket and all of the exhaust that got it moving. You will see that the whole rocket + exhaust system is still holding still.
You would see a (relatively) slow moving and heavy rocket moving away from very fast-moving, lightweight rocket exhaust.
Latest Answers