Jets use oxygen from the air to burn their fuel. Since rockets travel in space, they have to carry both oxidant and fuel. The oxidant may be oxygen or it may be another chemical substance, rich in oxygen. Many different fuels must be used in rockets. But all rockets must be able to give out a great deal of energy very quickly. Firework rockets use a solid mixture that contains both fuel and oxidant. Most modern rockets use liquid fuels but the NASA space shuttle uses two enormous solid fuels boosters, which use a powdered mixture of aluminium perchlorate, aluminium oxide and iron oxide mixed with rubber to form a solid block. Each booster uses 560 tonnes of fuel at a rate of 4.7 tonnes per second and is burnt out in only 2 minutes, when it is discarded.
Liquid fuel rockets usually use liquid hydrogen as the fuel and liquid oxygen (LOX) as the oxidant. The hydrogen and oxygen are carried in liquid form because they take up less room than as gases. They are liquefied by a combination of high pressure and very low temperatures. Each of the 3 liquid fuelled propellants on the space shuttle uses 500 kg of fuel every second. The advantage of liquid fuelled rockets is that they can be controlled; once you have lit a solid fuel rocket you cannot turn it off. The disadvantage of liquid fuelled rockets is that the pumps and piping which are needed have to withstand the extreme temperatures and vibrations.
Together the 3 main propellants and the two shuttles to the side of the rocket give a thrust of more than 30 times the weight of the loaded shuttle. This accelerates the shuttle to a speed of 4800 kilometres per hour in 2 minutes, by which time it has reached a height of 45 kilometres above the earth. Once the shuttle has reached the height of about 208 kilometres above the Earth and reached the speed of 27,000 kilometres per hour, the engines are turned off and the shuttle orbits freely above the Earth's atmosphere however still some fuel is used.
But why does the rocket actually move?
If you think about it, in order for the rocket to go up it has to push against something. We know it has to push against something because rockets work by a scientific rule called Newton's third law of motion. Isaac Newton listed three Laws of Motion over 300 years ago which stated that for every action, there is an equal and opposite reaction. In the case of Rockets the rocket pushes on its exhaust. The exhaust pushes the rocket, too. The rocket pushes the exhaust backward. The exhaust makes the rocket move forward.
If you don't get how it works, think of a rocket engine like a balloon.
If you fill a balloon with air and hold the neck closed there is no force or net force in any direction because the force is equal inside the balloon.
If you release the neck of the balloon, there is now a hole. This make the force imbalanced because the internal pressure on the front of the balloon is greater than the internal pressure on the back of the balloon.
This results in a net force acting forward on the balloon--thrust. The balloon flies forward under the because of the thrust, and the air coming out of the back of the balloon is the equal and opposite reaction to the thrust like what Isaac Newton stated.
Liquid fuel rockets usually use liquid hydrogen as the fuel and liquid oxygen (LOX) as the oxidant. The hydrogen and oxygen are carried in liquid form because they take up less room than as gases. They are liquefied by a combination of high pressure and very low temperatures. Each of the 3 liquid fuelled propellants on the space shuttle uses 500 kg of fuel every second. The advantage of liquid fuelled rockets is that they can be controlled; once you have lit a solid fuel rocket you cannot turn it off. The disadvantage of liquid fuelled rockets is that the pumps and piping which are needed have to withstand the extreme temperatures and vibrations.
Together the 3 main propellants and the two shuttles to the side of the rocket give a thrust of more than 30 times the weight of the loaded shuttle. This accelerates the shuttle to a speed of 4800 kilometres per hour in 2 minutes, by which time it has reached a height of 45 kilometres above the earth. Once the shuttle has reached the height of about 208 kilometres above the Earth and reached the speed of 27,000 kilometres per hour, the engines are turned off and the shuttle orbits freely above the Earth's atmosphere however still some fuel is used.
But why does the rocket actually move?
If you think about it, in order for the rocket to go up it has to push against something. We know it has to push against something because rockets work by a scientific rule called Newton's third law of motion. Isaac Newton listed three Laws of Motion over 300 years ago which stated that for every action, there is an equal and opposite reaction. In the case of Rockets the rocket pushes on its exhaust. The exhaust pushes the rocket, too. The rocket pushes the exhaust backward. The exhaust makes the rocket move forward.
If you don't get how it works, think of a rocket engine like a balloon.
If you fill a balloon with air and hold the neck closed there is no force or net force in any direction because the force is equal inside the balloon.
If you release the neck of the balloon, there is now a hole. This make the force imbalanced because the internal pressure on the front of the balloon is greater than the internal pressure on the back of the balloon.
This results in a net force acting forward on the balloon--thrust. The balloon flies forward under the because of the thrust, and the air coming out of the back of the balloon is the equal and opposite reaction to the thrust like what Isaac Newton stated.