If space is a vacume, then by definition there is nothing there. so when a rocket thruster goes off and it has nothing to push against, then how can it move the rocket?
2006-07-26 02:05:17 · 16 answers · asked by tklondon 1 in Science & Mathematics ➔ Physics
Propulsion
2006-07-26 02:08:00 · answer #1 · answered by Anonymous · 0⤊ 0⤋
A rocket doesn't "push against something" to move. Neither does a jet engine, or a jet ski.
The propulsion of a rocket is based on the application of Newton's 3rd Law of Gravity - every action has an equal but opposite reaction. In simple terms, a force acting in one direction produces a reaction of the same amount in the other direction.
So in the case of a rocket, when the fuel is burned the force of the hot gasses escaping through the rocket's exhaust creates an equal force acting in the opposite direction. If the gasses escape to the rear, the reaction force acts in the forward direction and the rocket moves forwards.
It's the same action that causes guns to recoil when fired - as a bullet leaves the gun, the force of the bullet creates an equal force acting in the opposite direction and this is felt as a recoil.
2006-07-26 02:15:40 · answer #2 · answered by k² 6 · 0⤊ 0⤋
The law of recoil,
also one of Newtons three laws (number 3 I think)
If you fire something in one direction ie a canon ball, there will be a push of exactly equal force in the other direction (recoil)
So a rocket fires lots of tiny balls out it's back end and moves off in the opposite direction due to the recoil. This works better in space that on earth as theres no atmosphere to be slowed down by and gravity is not interfering much.
Interestingly an american science journalist in the 1920s pointed out that 'it wuld be impossible for rockets to work in space as there is no air to push against'.
2006-07-26 02:14:27 · answer #3 · answered by mince42 4 · 0⤊ 0⤋
this is an occasion of action-reaction. you are able to keep in mind from college: "for each action there is an equivalent and opposite reaction." whilst it comes to a rocket in area, the reality that a jet of gasoline is being pushed out the lower back, (the action), produces an equivalent and opposite reaction, (the thrust), pushing the rocket forward. the reality that a rocket close to the floor, (on your backyard), has no longer something to do with the reality that the rocket is "pushing" itself forward - it is not pushing against the air, gravitational forces, etc. sure, this is combating the opposition of gravity, despite if it is not pushing against it. (See the version?) making a rocket does not even require a flame - you are able to make a rocket using water, or maybe air rigidity to grant thrust, and a great variety of have finished so. All you like is a few thing, (a gasoline - inclusive of plasma or an ion beam - or a liquid), shooting out the lower back of the rocket and it ought to have forward thrust - no count in case you're in area or your lower back backyard. The extra cloth (mass) is expelled, and the faster this is expelled, the extra thrust the rocket could have.
2016-10-08 08:20:18 · answer #4 · answered by rotanelli 4 · 0⤊ 0⤋
Because space is a vacuum, this is the very reason that rockets are used in space. Jet engines rely on having air to move through them to work which is why they won't work. Put simply, as rockets are burning fuel and expelling it from the craft, this is where the propulsion comes from, no need for air.
2006-07-26 08:12:37 · answer #5 · answered by Lewiy 3 · 0⤊ 0⤋
Pressure.
The thruster creates pressure. Space attempts to equalise the pressure with itself. In simpe tems the side effect is movement.
If you fill a bottle with air and seal it, then immerse it in water. You will find more resistance, the deeper you go. If you let go. The bottle will shoot up. Even though gravity goes down. The water is trying to equal the pressure in the bottle. It can't get inside it so it gets pushed to an area where the pressure is equal.
I suppose you could say that pressure is determined by the density and weight of molecules.
2006-07-26 02:16:44 · answer #6 · answered by JeffE 6 · 0⤊ 0⤋
The heat from the burning fuel comes out in the opposite direction to the movement of the rocket. These gases come out applying lot of pressure on the rocket which results in forward movement of the rocket, a result of Newtons third law of motion.
2006-07-26 02:13:42 · answer #7 · answered by Anonymous · 0⤊ 0⤋
You really think the rocket is pushing against the air down here on earth ? Since air is less dense that the rocket, it would also not move here either. Think a little harder. Hint, it has something to do w/ equal and opposite reaction. PS the word is "vacuum' one of the few words w/ a double 'u'
2006-07-26 02:12:41 · answer #8 · answered by tjc 2 · 0⤊ 0⤋
"for every action there is an equal and opposite reaction"
although there is nothing for the exhaust gases to push against once they exit the nozzle, there is a tiny region where the gases are forced together by the narrowing of the nozzle combined with the effect of their expansion by combustion.
The result is that the hot gases which continue to expand push in all directions, including the direction of the nozzle opening where more hot gases are pushing outward. The two opposing forces result in the push which moves the rocket.
2006-07-26 02:13:39 · answer #9 · answered by kittybriton 5 · 0⤊ 1⤋
The movement of the high-speed exhaust in one direction propels the rocket in the opposite direction. This is Newton's Third Law of Motion in action; for every action there is an equal and opposite reaction
2006-07-26 02:12:56 · answer #10 · answered by diadomraz 1 · 0⤊ 0⤋