Phys220A homework help

PHYS 220A

30 November 2015

Endeavour Space Shuttle

The visit to Endeavour Space Shuttle in Los Angeles provided me with a deeper insight of how physics principles are applied in real life. Not only did I learn of how the rockets get propelled into space, but also gained a better understanding of how the satellites are injected into orbit after the rocket gets into space. As I strolled into the facility, I was excited since I finally had the chance to get the answers to the several questions that crammed in my mind regarding rockets and satellites. Before the visit, questions such as how does the spacecraft travel with accuracy and know where it’s going? Once it reaches the orbit, what keeps it in motion? Besides, can any place be chosen for the launch of the rockets? Even more importantly, I was fascinated to learn the various structural parts of the rockets and the fuel used in its operation.

The process of rocket propulsion was illustrated to me just like I had learned in my theoretical physics. Essentially, a rocket is propelled forward due to a rearward ejection of burned fuel that was initially in the rocket. Consequently, the forward thrust gained by the rocket is as a result of the back force of the ejected burning fuel. In the end, the rocket propulsion principle confirmed Newton’s third law of motion which states that action and reaction are opposite yet equal forces. Unlike the jet engine that depends on drawing in air to burn the fuel, the rockets utilize the fuel on board which is a mixture of liquid oxygen and hydrogen to cause combustion ensuring that they can operate in space where a vacuum exists. I was also intrigued to learn that the rocket didn’t work on the principle of pushing against the ground, or air but depended solely on the thrust force provided by the burning fuel. I also realized that for a large weight of rockets is dominated by fuel. As such, for massive uplift force to be achieved by the rocket, the fuel has to be burned at a rapid rate. This would ultimately ensure that the rate of change of momentum is huge and therefore causing the propulsion force to be sufficient to cause uplift. Certainly, this principle was in line with Newton’s second law of motion which suggests that the magnitude of force on a moving body is directly proportion to the rate of change of its momentum {F = (v-u)dm/t}.

The second fact that I learned at the science facility is that the earth is shielded from radioactive particles from the sun by an electromagnetic field around it. As such, when the rockets pass through the layer of the earth’s electromagnetic field, it may get charged and risk burning when leaving or entering the earth’s atmosphere from space. Therefore, the rocket’s nose is designed to be curved instead of being sharp pointed in order avoid the concentration of charges that may in the end build an electrical potential difference capable of destroying the rocket. Certainly, this principle reiterated the electrostatic charging process by induction that causes a body to attain an opposite charge to the one charging it, creating a difference in potential that massive force of attraction to develop.

Additionally, I was amazed to learn that the astronauts have to content with low gravity such as that of the moon that is 17% that of the earth. The simulations at the facility proved that walking in other planets with less gravitational force can be quite a challenge since one finds himself running even when applying less effort in movement. I managed to grasp the concept that the weight of a body is inversely proportional to the square of its distance from the center of the earth. Consequently, when the astronauts are in space or other planets they seem to be floating due to their less weight which decreases as they move away from the center of the earth. Therefore, for the spaceship crew to maintain order in the rocket’s cabin, robots are used to move items and prevent them from floating in a disorderly manner. In the end, I appreciated the concept learnt in class that the acceleration due to gravity experienced by a body is independent of the mass of a body but depends on the mass of the earth Me, radius of the body from the earth’s center Re, and a Kepler’s constant of proportionality, G so that g = (GMe/Re2).

Moreover, I was informed that the launching sites of rockets are strategically chosen so that they are of the shortest distance to the orbit that a satellite is to be launched. This was crucial to ensure that the corrections done for the travelling rocket and satellites are minimal. Once the spacecraft was in space, it entered the orbit and ceased using its fuel and instead enjoyed the earth’s force of gravity and continually fell around the earth rather than towards the earth. Ultimately, it was kept in a uniform circular motion at a constant speed. I was delighted to notice that the scientists at the facility use the centripetal force equation to equate to the weight of the satellite when considered from the earth. In the end, they were able to find the circular velocity that would enable them reach at a designated point and hence launch their satellite after a predetermined period of time.

The circular orbiting velocity of the spacecraft was noted to be dependent on the mass of the earth and radius of the orbit just like was learnt in class that v = (GMe/r). In fact, the scientists explained that a small space shuttle that resembles a plane craft in size can orbit in space for up to one month before the collisions with particles finally slows it down and make it fall from the orbit. Besides, I realized that the astronauts are usually in a state of apparent weightlessness because they possess the same velocity and acceleration as the space shuttle and there is no gravitational force to push them against the walls or floor of the shuttle.

By the end of my visit, I was convinced that indeed the physics principles learnt in class are practical and interesting to implement. Certainly, by using gravitational principles between planets, combined with equations regarding circular motion, the scientist are able to predict the final destination of the rocket and its duration to reach the target. However, I guess I still have a lot to learn regarding the finer engineering principles that make the rockets operate the way they do. From the visit to Endeavour Space Shuttle, I know that it is not ‘rocket science’ to learn how rockets actually get launched into space.