Question: how do rockets work??????:):)

John Welford answered on 3 Jul 2012:

The term “Rocket” relates to the way an object creates its thrust. So a missile, a spacecraft or a vehicle could be a rocket if it is powered by a “rocket engine” (also sometimes called a “rocket motor”). So I’ll describe how a rocket engine works and you can imagine strapping one to whatever vehicle you have in mind!

Most engines and motors push themselves along with force against another object. In a car this is the road through the friction of the wheels. In a plane this is by forcing the air backwards. Rockets work by reaction force (this is Newtons third law), this means that they can work in space where there is no road or air to push against.

Try thinking about this experiment (or try it out for yourself!). You’re sitting in a small inflatable boat on a lake trying to make it move. One option is to pull yourself along using a rope tied to the shore. This is how a car moves, by forcing against a solid object. Another option is to paddle yourself through the water or use a propeller under the water. This is like how an aircraft moves, by forcing against a fluid (or gas). Now imagine you have a friend in another boat next to you, and you push them away. You will both float off in opposite directions. This is how a rocket engine works, by throwing out mass backwards in order to push itself forwards.

If your friends boat is a lot lighter than yours then you will find that they travel away from you at a higher speed. This is called the “conservation of momentum”. Also the faster you push them away, the faster you will both travel.

You can imagine any two things being thrown apart to get the same effect. An astronaut throwing ball in space, or you pushing a friend away when you are both sat on wheely chairs.

Rockets explode fuel in their engines and the resulting gas is thrown out behind them, pushing them forwards. The faster the gas when it comes out, the faster they accelerate forwards. There is a lot of science involved in getting the gas to come out as fast as possible, but that is the basic principle!