How a Rocket Works

If you blow up a balloon and tie its neck, the balloon does not mo ve If you untie the neck,the air rushes out and the balloon flies madly around the room. when the neck is tied the air inside the balloon pushes equally against the rubberskin in all directions. when you untie the neck, the air can escape on direction. A rocket engine works in just the same way. fuel is burnt inside the rocket and produces hot gases. the gases can escape from the back of the rocket, but their forward pressure drives the rocket forward. A rocket engine is more powerful than any other type of engine it can move a spacecraft or other object fast enough to escapethe earth’s the neck side . however it is still pushing against the skin on the side opposite to the neck . as a result the balloon moves in this gravitational pull.the gravitational pull or force of gravity is the force that makes objects fall to the ground when they are dropped.it pull’s them to words the centre ofthe earth. the minimum speed required to escape from gravitational pull is 40000kms an hour 11 kms a second. this speed is called escape velocity. At speeds lower than escape velocity, a spacecraft moving away from earth would gradually slow down then fall back to earth. GETTING INTO SPACE Travel in space is on of the greatest adventures In history. for hundreds of years, people dreamt about travelling in space, just as they dreamt about flying space travel has been possible only since suitable rockets were devopled in the I95os. Space travel has many problems. in the past,two problems were more difficult than any others. the first was making an engine that was able to work in space, were there is no oxygen. the other was making an engine powerful enough. both of these problems were solved by the development of the rockets. SPACE ENGINES no petrol engined aircraft can fly in space. its propellor can work only where there is air. even an ordinary jet engine will not work in space because it needs oxygen from the air to burn its fuel. a rocket engine also needs oxygen to burn its fuel. so, it carries Its own oxygen with it, eithetr in its fuel or in a seperate tank. SATELITE AND PROBES

The first objects carried into space by rockets were artificial satelites and probes later, human beings travelled into space and space craft. ARTIFICIAL SATELITES rocket carried these into space. PROBES unmanned space craft are sent to the moon and the planets to find out more about them. radio transmitters in probes send photographs and information back to earth.