The answer is very simple: Recoil.
Surely you are familiar with the concept of recoil? The most famous example of this is, of course, with firearms: When you shoot one, you get a "kick": The firearm experiences a strong force back, ie. the opposite direction that the bullet goes to. That's recoil.
(The reason why that happens is due to conservation of momentum, but that's not all that important. The important to thing is to understand that it happens, and firearms are the perfect most practical example.)
And yes, the exact same recoil happens even if the firearm is shot in a vacuum: Put one in a vacuum chamber, suck all the air out, and fire it using some mechanism: It will experience the exact same recoil. It being in air or in vacuum makes no difference.
And this happens with everything: Push a friend with great force, and you will be shoved back in the opposite direction by your own push. That's also recoil.
If you were floating in a weightless environment (even in vacuum), if you throw a ball, you will experience an acceleration towards the opposite direction. The amount of acceleration is proportional to the mass of the ball and how fast you threw it. Throw it faster, and you will experience stronger recoil in the opposite direction.
Shooting gas instead of a ball has the exact same effect: You will also experience a recoil that's proportional to the mass and velocity of the gas being ejected.
And that's exactly how rockets work in a vacuum: They eject massive amounts of gas at staggering speeds (which is what burning the gas with oxygen allows.) The rocket essentially experiences recoil because of shooting that gas at such amounts at such high speeds.
It's as simple as that.
Comments
Post a Comment