HELP IN ROCKETS! when rockets take off and when in flight what do they 'push against' to accelerate ????

Question

and also in space???

Answer 1

Yes, equal and opposite reaction.

An excellent resource below - better explanation than I could come up with and lots of other facts, too.

Answer 2

A rocket engine is a type of jet engine. Jet engines provide thrust by expelling gas or fluid particles out the exhaust at a high velosity. In most cases they use fuel and unbalanced pressure in a combustion chamber to convert heat energy into kinetic energy. The major difference between a rocket engine and the engines you find on other aircraft is that a rocket carries it's fuel and an oxidizer so it can operate where the atmosphere doesn't provide enough oxygen or in space where there is an absence of oxygen. Also, a rocket gets the majority of it's thrust not from the particles escaping the exhaust, but from those gasses rapidly expanding and putting pressure on the inner walls of the rockets cone shaped exhaust nozzels.

One should also note that rockets are not very efficient at low speeds. As the rockets accelerates, and fuel is used up making it lighter, the effect of the gasses pushing on the exhaust nozzels is much more productive.

Don't confuse jet propulsion with the mechanism that moves helicoptors through the air. A helicoptor's blades are not fan blades. They are little rotating wings. They provide lift because their airfoil shape causes a pressure differential between the air moving under the blade as opposed to the accelerated air moving above the blade. By changing to angle of the blades collectively of cyclicly you can control the helicoptor's velocity or direction of movement.

There's some very informative articles about this on the internet. You can go to wikipedia and look up Jet Engines, Rocket Engines, and Newton's Third Law of Motion: The Law of Reciprocal Actions.

For Helicoptors look up Helicoptors. It would help to know about Wings, Bernoulli's principle, the Coanda effect. and Aerodynamics.

Finally read up on Momentum, and more specifically Conservation of Momentum. Understaning this will provide a lot of insight into the physics of flight, propulsion, fluid, and aero dynamics.

Answer 3

A rocket does not need to 'push against' anything. Newton's law doesn't require anything to push against... which is why rockets work well in the vacuum of space. What is doing the (opposite) pushing is the pressure of the burning propellants in the direction of the rocket's flight. Towards the rear these gases are free to escape so they don't exert a force on the rocket, but toward the front they are constrained by the combustion chamber. The forces are not balanced so there is a net force pushing it all forward.

Answer 4

To make it simple...they push against themselves. The gasses coming out of the nozzle at the end of the rocket are shooting out extremely rapidly, and for every action there is an equal and opposite reaction. So at the same speed the gasses leave, the rocket is propelled in the opposite direction. Kind of hard to comprehend but just think about forces other than physically "pushing" on something. Astronauts can move about in zero gravity by using their own moment and creating new amounts of acceleration by using body movements (acceleration is defined as velocity and direction). The gasses in the rocket go one way, and the rocket goes the other way at the same momentum.

I just thought of the cannon/cannon ball thingy to help. Momentum equals mass multiplied by velocity (M=m x v or M=kg x fps)Ok, a cannon ball is shot out of a cannon at 2000 feet per second and the cannon ball has a mass of 1 kilogram. That means the cannon ball's momentum is 2000. But, for every action there is an equal and opposite reaction, meaning that the cannon also has to have a momentum of 2000, but it is not moving at 2000 feet per second. If the cannon has a mass of 2000 kilograms, that means it will be moving at only 1 meter per second, but will still have the same momentum as the cannon ball. Try and apply this to the rocket except with the gasses of the rocket being the cannon ball and the actual rocket being the cannon.

Answer 5

Some of these answers are more or less on the right track; but simply put, the rocket pushes against the gases that are in the combustion chamber. If you push on something and manage to push it AWAY from yourself, then it will push back on you by the same amount. If you ever get stuck on the ice in the middle of a frozen lake, take the heaviest thing you have, and throw it as hard as you can--it will push back on you, and you'll go sliding.

Answer 6

Rocket fuel has an oxidizer in it. It has air built so to speak. The burnt particles are what it pushes against. the oxidizer also explains why rockets work in space

Answer 7

for every action there is an equal and opposite reaction, untill slowed down by air resistance friction or other outside forces.

There is no air or friction in space which is why spacecraft can attain such high speeds.