While traveling in space the machine should required a jet But in space how the 3rd law of motion helpful?

Question

For moving forward the machine in space requires a back ward jet.
But in space to which the jet pushs back.
How the Newton's third law work there?

Answer 1

Suppose you are taking a space walk near the space shuttle, and your safety line breaks. How would you get back to the shuttle? The thing to do would be to take one of the tools from your tool belt and throw it is hard as you can directly away from the shuttle. Then, with the help of Newton's second and third laws, you will accelerate back towards the shuttle. As you throw the tool, you push against it, causing it to accelerate. At the same time, by Newton's third law, the tool is pushing back against you in the opposite direction, which causes you to accelerate back towards the shuttle, as desired. This is the principle behind jet propulsion: a jet rocket expels fuel rapidly by ``pushing against it''. By the third law the fuel exerts an equal and opposite force against the rocket so the rocket accelerates in the opposite direction that the expelled fuel goes. Another example of the 3rd law is a book lying on a table. If the table were not there the book would fall under the force of gravity between the book and the earth. Why then doesn't the book move off the table, in accordance with the 2nd law? The table is exerting a force on the book that is just enough to cancel the gravitational force on the book. By Newton's third law, the book is also exerting an equal and opposite force on the table, and this is why the table feels the weight of the book. If the book were very heavy, its weight would cause the table to bend, or even break. This is illustrated in the following figure.

The answer to this question comes from the third law. Imagine the skateboard again. On the ground, the only part air plays in the motions of the rider and the skateboard is to slow them down. Moving through the air causes friction, or as scientists call it, drag. The surrounding air impedes the action-reaction.

As a result rockets actually work better in space than they do in air. As the exhaust gas leaves the rocket engine it must push away the surrounding air; this uses up some of the energy of the rocket. In space, the exhaust gases can escape freely.

Answer 2

Inside the rocket there is a gas chamber. Gas is burnt inside the chamber.

If there is no outlet, the pressure will be enormous so as to break the chamber and all parts of the chamber will be made to pieces which will fly of in all directions.

However, we are not allowing the chamber to explode. There is an outlet for the gas to come out of the chamber. The enormous pressure of the gas pushes the gas outside the chamber (rocket).

If there WERE NO OPENING, the pressure acts in both the front and back of the rocket equally. The rocket cannot move. (Of course, in all directions the pressure acts equally; but we consider the pressure acting along the direction of the opening alone)
Now since there is an opening at the back, there is an unbalanced force which acts on the rocket in the forward direction alone. Hence the rocket is pushed forward.

In terms of Newton’s third law, we can say that the rocket pushes the gas outside and hence the gas pushes the rocket forward.

Answer 3

The propellant expelled from the thruster is what the machine "pushes against."