Can a rocket move faster than the air it expells?

Answer 1

ABSOLUTELY! The exhaust of the space shuttle is significantly less than the 17,000 or so MPH it requires to be traveling to remain in Low Earth Orbit (LEO). The escape velocity required by the Saturn V rockets which took astronauts to the moon and back was about 25,000 MPH! I don't know the velocities of the rockets which flew to Venus, Mars, Jupiter, etc, but they required significantly more speed yet.

ALL these vehicles are multi-stage rockets, burning significant amounts of fuel to push heavy loads through the near-Earth "gravity well", but as they climbed they dropped heavy sections no longer needed for the flight. In the rarefied (and near vacuum) regions of "space" (above about 100 KM or 62+ miles) the lack of drag on the vehicle allows all the COMBINED mass of exhaust to push the vehicle at ever higher and higher velocities, eventually exceeding the exhaust velocity of the motor by a significant amount.

Answer 2

Yes it can. The rocket equation says that a rocket which expels all but 1/e of its initial mass as exhaust will be moving at the same speed as its exhaust, where e is the base of the natural logarithm and is equal to about 2.72. If it expels more than that, it will move faster. So to move faster than its exhaust, more that 2/3 of the initial weight of the rocket must be the fuel and it must burn it all. This is why we need giant rockets to put tiny things in orbit.

Answer 3

Yes, a rocket can move faster than the gas it expels.

Rockets work on the principle of "Conservation of Momentum". Momentum is defined as "mass times velocity". The gas the rocket expels has both mass and velocity in one direction, and this gives the rocket an equal momentum in the other direction.

Assume a 100kg (mass) rocket burns 90% of its mass as fuel and that burning this fuel in the engine gives it an exhaust velocity of 10 meters/second. That gives the fuel burned a total momentum (or "impulse") of 90 kg times 10 m/s = 900 kg*m/s. Since the remaining rocket has to have an equal momentum and the remaining rocket weighs 10 kg, you can divide that into the fuels' momentum to get a rocket velocity of 900 kg*m/s divided by 10 kg for 90 m/s rocket velocity. Note that this was accomplished with an engine that only imparted 10 m/s velocity to the exhaust gas, but that the final rocket velocity was 9 times that fast.

Answer 4

Yes, when gravity is adding to the equation. The rocket does indeed work on the pressure principle..... we say it is reaction but reaction is a shorthand way of saying what happened in the equations. It gets boring as all heck to have to say all that stuff each time we want to describe a rocket in the air so rational men agreed to bypass it and get to the end and call it reaction. Ion reaction works the same way. You expel an ion out the back. The mass and acceleration of the ion gives you a force that is going to be useful up to near the speed of light.

Mother nature loves everything in balance - The pressure force that is pushing the downwash air down is the gravity force trying to pull the air down into the vacuum. The pressure force that is caused by gravity is pushing the wing up is reacted by the wing. Mother nature abhors a vacuum - ever hear of that? The air above rushed in and the air below would do the same but the wing is in the way so the air below pushes the wing up in front of it.

Answer 5

The solutions in this thread do not look to tell apart between rockets in area or rockets leaving earth. human beings point out 11 Kph yet fail to comprehend that it particularly is the Earth's get away velocity and rockets ought to accomplish that velocity with a view to get out of Earth's gravity. As mentioned by making use of an different contributor the only predicament to velocity is the gas you are able to hold. One thought for a deliver is to harness hydrogen from area as gas thereby negating the ought to hold gas.

Answer 6

If the rocket flies on a leveled flight or if it's climbing, then it's not possible, because the drag will decrease the rocket's speed.

But, if it's coming down, then the gravity will increase the speed.

Answer 7

Ony if some other force is working on it (gravity for example) but absent other forces, only if the "air" or exhaust is more massive than the rocket itself. Which is basically impossible.

Answer 8

Yes.

You folks really shouldn't answer factual questions unless you actually know the answer.

Answer 9

no because it can go faster then a speed of light and its everywhere so it can be in the place where everyone is