# Physics Revision Essay

Several years after his death, the US government for \$1 million, showing how the opinion of society had changed due to scientific discoveries and achievements, bought Goddard patents In a vacuum, there is no air but rather an absence of any matter. The most special thing about a vacuum is the way the dispersion forces work. Dispersion forces that old a lot of substances together now work in reverse as the substance attempts to fill the space in which it is occupied (which is boundless). As such there have been serious concerns in the past about whether or not a rocket could travel in a vacuum. To understand this, an understanding of how a rocket works must be achieved.

A rocket works through the Law of Conservation of Momentum ( NV 0 0 mum ), and Newton’s 2nd and 3rd laws of motion ( F 0 ma and every action has an equal and opposite reaction, Fl 0 0 IF) [HE]. By this it is meant that a rocket is a reaction engine, what it does, has an affect that in turn powers the rocket. Through combining the NV 0 mum (force = change in momentum / time) equations we get The matter is caused by a combustion reaction that releases chemical potential energy and converts this to kinetic energy, moving it out of the engine of the rocket at a high velocity [HE]. Despite this matter weighing very little, the velocity that it comes out at means that it has a relatively high momentum, compared to being stationary.

This in turn through the law of Conservation of Momentum means that the rocket is moved in the opposite direction to the direction that the matter is thrown out of [HE]. Then although the rocket has a reaction force acting upon it, the effect of this force is divided by the time over which it is felt. In some modern rockets the thrust can be greater than 3. Xx N; however Newton’s 2nd law of motion means that the acceleration of the rocket is the force divided by the mass, significantly lowering the acceleration [HE]. So the contribution from Goddard towards this aspect of rocketry was not the theory, but rather the testing of the theory. He did this through the use of a ballistic pendulum with a rocket and a rocket at first, measuring the height the rocket with sock reached on the pendulum.

Years later he tested the theory again through the use of a calibrated spring and firing the rocket into it, calculating the thrust and proving that there needed to be no air to push against for a rocket to provide thrust. This allowed for the commencement into the development of space exploration There are a number of advantages to the use of liquid fuel rockets over solid fuel rockets. These include: 0 Liquid rockets able to be stopped once started 0 Able to be pumped through pipes -physics Variable thrust Boosters are more re-useable than solid rocket boosters However there are disadvantages to liquid fuelled rockets: 0 Fragile (they contain many complex parts) 0 The liquid oxygen must be kept liquid (-CO’S) 0 Less thrust per size than solid fuelled rockets Liquid rockets, however, still use combustion reactions.

Combustion reactions release heat and kinetic energy when the chemical potential energy is released from the compounds. The rocket immediately uses the kinetic energy, however the sound and heat energy needs to be transferred to another device to convert them into kinetic energy [HE]. A picture of one of GoddardГ? patented Rockets fired by solid fuels http://www. Google. Mom/patents? Id=I jabbered=abstract =gbs_overview_r=o#v =monopole=false Attachments to Rockets While proving that rockets could work without the presence of air to push against, he also measured the efficiency of which rockets use the chemical energy released by the combustion of various materials.

By firing a rocket whilst submersed in water, he found that only about 2% of the amount of energy available in the chemicals being used was actually being used in the thrust of the rocket. This was calculated through the rise in the water temperature, and calculated using the specific heat capacity of eater. To solve problem with the waste of energy, Goddard looked at ways of converting this Wasted’ energy into the thrust of the rocket. As most of this energy was lost as heat, Gustavo De Lava who had designed a steam turbine that could reach speeds of faster than the speed of sound relative to the surface of the earth, had already solved the solution to the loss of heat for Goddard [HI]. This device transferred the heat energy into the turbine, and then converted the heat energy to kinetic energy through using steam [HE].

The use of this steam turbine increased the heretical efficiency of Goddard rockets to roughly 60%, greater than other steam powered turbines due to the temperature at which a rocket operates. This increased the amount of matter being propelled backwards thus increasing the thrust of the rocket, as discussed earlier. He developed pumps suitable for the rocket fuels, cooling rocket motors and other such contraptions designed to carry man to outer space. Goddard prototype rockets reached an altitude of 1. Exam (1. Km). These inventions have allowed for the commencing research into space exploration and as such have had a significant impact on the space community. Another area that Goddard looked deeply into was that of guided rockets.

In this area he used gyroscopes to control the motion of the rocket while it was in flight, steering the rocket with small vanes in the sides of the rocket. This allowed the motion of the rocket to be predicted and a suitable landing point constructed. Gyroscopes work using the law of conservation of momentum, and stay unchanged relative to a set point [HE]. This means that if a gyroscope was used and spun around in circles, the centre of the gyroscope would still be unchanged (not spinning) relative to the starting point, even if the rest of the object was. -physics Receiving his PhD in 1934, Werner Von Braun was, for almost half his life, a German rocket scientist.

His life crossed over that of American scientist Robert Goddard, who influenced his work in the field of space exploration through his work in the field of liquid rockets, and thereafter the field of space exploration. Having seriously entered the field of rockets in 1932, Von Braun was doing his work in the field of liquid military potential of these rockets were realized by the military, a research grant was given to Braun, and two years later he received his PhD at the university of Berlin, his thesis had its name changed due to its altruistic nature. Soon after, Braun and his group of rocket scientists successfully launched rockets that rose to over 2. Km in the air, however all rocket tests were forbidden so this was done through the military. From this point onwards, Braun did all his work under the military. For the entirety of his life in the U. S. , he claimed that patriotic motives (do it or get shot) outweighed any moral obligations over the course of WI. One of Bran’s most notable achievements was the creation of the V-2 missile (Vengeance Weapon 2), originally named the A-4 missile. This particular rocket contained gyroscopic intros and could hit a target at a distance of up to km and accurately hit a large target (city etc) at a distance of up to km, and as such it was one of the greatest weapons of WI.

Reaching an altitude of above km, the British knew it as ‘death from above’ and at the time was the closest to outer space that any rocket had been. There were several major technological advances in the V-2 that surpassed previous rockets [HE]. These were: 0 The power supplied by the engine (liquid ethanol with liquid oxygen in a small combustion chamber) 0 The shape (shaped like a bullet) 0 Guided missile (inertial guidance system using gyroscopes) Radio transmission (used mainly during development) The most significant advantage of the V-2 rocket though, was not the distance the rocket traveled but rather the speed at which impact occurred.

Due to the vast -physics amounts of gravitational potential energy gained when the rocket is fired, the rocket approaches the surface of the earth at above the speed of sound (the rocket actually hit targets at about mom/s) [HE]. This meant that there was a sonic boom literally milliseconds before the rocket hit, there was no warning Just an explosion and people dead. This meant that there was no available defense for those targeted, Just hoping hat the missile would miss due to its inaccuracy at hitting small targets. Although the V-2 was a leap in the technology behind rocket science, the technology behind it was, in the main part, developed by Robert Goddard, an American scientist.

The engine of the V-2 is very similar to that of rockets built by Goddard and the guidance system was developed by Goddard only years before [HE]. The only major differences between the rockets were that the V-2 was much bigger and had a lot more money spent in its development, for example the engine of the V-2, though similar, is much egger and more complicated, containing over a million parts.. The Explorer 1 was the actual rocket in which the American dream of traveling into space was achieved. The satellite was only about keg, however was fitted with instruments that allowed for the detection of layers in the atmosphere, and confirmed that the theory of the Van Allen Belts around the earth.

The significance of the Explorer 1 was not that it was the first man-made object in space (the Soviet Union did it first with Sputnik and Sputnik 2 carrying a dog) but that the Americans could actually get something into orbit around the earth [HI]. Satellites today provide electrification, GAPS, TV and many other services to those on the surface on the earth, and all of it started with the Sputnik series satellites [HE]. The Apollo 11 mission was the mission that got the first man on the moon. At the time of the operation, Braun was the director of the NASA George Marshall Space Flight Centre, and he had helped in the development of several space launch vehicles; Saturn l, B and V.

These were the boosters used to force the rocket into outer space, and therefore were the boosters that put the man on the moon. With over a million parts in each of the different types of Saturn boosters, it was no small feat in reducing the boosters, which, with the Saturn V produced over 3. Xenon of thrust on takeoff (refer to http://www. Bragging. Us/space/specs/Saturn. HTML for full specifications on all the Saturn boosters). This may be a large amount of thrust, but to lift a mass of 2. Xx keg, the actual force on every kilogram is 1 IN, or 1 . 1 G’s (F=ma, Newton’s 2nd law of motion) [HE]. To counteract gravity (lift the rocket off the ground) requires 1 G so the initial acceleration of each Saturn booster on Apollo 11 was 0. G or 1 m/SAA. This acceleration increases though as the fuel is burnt, also due because the 3. Xenon of thrust is parade over a smaller mass, the acceleration is larger. However maximum allowable acceleration felt by the -physics astronauts in the rocket is g’s, or mom/s upwards (gravity accounts for the extra G). But the effect of the earth’s gravity lowers as the rocket gets further away from the centre of gravity so as the rocket gets higher, the allowable acceleration stays the same but the change in velocity increases (the acceleration increases) to mom/SAA due to gravity no longer accounting for an extra G in the opposite direction.

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