### Ghost Writing Essays

Have you ever wondered what it would be like to fly in space or work on the crew at NASA that helps the astronauts get home safely? These two jobs both use many of the laws of physics. In fact, almost everything they do involves physics. Apollo 13 is a movie that epitomizes what those jobs are like and how much physics is required. The three main laws of physics in the movie were Newton’s Law of Universal Gravitation, Newton’s First Law, and Newton’s Third Law. One main law in Apollo 13 was Newton’s Law of Universal Gravitation, defined as F=Gm1m2r2, where G=6. 7? 10-11. The first main scene in which this law was needed was when NASA decided that it would be best for the crew to take a free-return trajectory back to Earth. Newton’s Law of Universal Gravitation was needed to figure out the net force and its direction on the Apollo 13 spacecraft as it followed its path. NASA made sure that Apollo 13 would make it back to Earth and not be lost in space. Another scene in which Newton’s Law of Universal Gravitation was needed was when the Apollo 13 crew needed to execute a burn.

This law helped them calculate the forces acting on them by other planetary objects, and therefore how much force their burn needed to apply. By simply adding together force vectors NASA could predict the exact location at any time of the Apollo 13 spacecraft. The third scene in which this law was required was when Jim Lovell stated that they “just put Sir Isaac Newton in the driver’s seat” after NASA had ordered them to power down both the LEM and the Command Module.

What Jim Lovell was stating was that since now they couldn’t do anything to control the ship the only thing guiding them to Earth were Newton’s laws, especially Newton’s Law of Universal Gravitation. If Newton’s laws were to fail then the Apollo 13 crew would have had no chance of getting home. To sum it up, three scenes in Apollo 13 that used or showed Newton’s Law of Universal Gravitation were when Jim Lovell said that they “just put Sir Isaac Newton in the driver’s seat”, NASA decided that a free-return trajectory was the best way to bring the Apollo 13 crew back home, and when Apollo 13 needed to execute a burn to adjust its course.

Another prevalent physics law in Apollo 13 was Newton’s First Law, which states that a body will persist in its state of rest or of uniform motion unless it is acted upon by an external unbalanced force. In most scenes of Apollo 13 that show the spacecraft in space this law was visually demonstrated. The Apollo 13 spacecraft was always in uniform motion unless it was acted on by another external unbalanced force. The most significant force in space that would act on the spacecraft was that of gravity.

Gravity from other large masses, such as the Earth, Moon, and Sun, acted as the external unbalanced force which changed the spacecraft’s speed and direction. If all the gravity in space were to suddenly disappear and the net force on the spacecraft were to be zero then the Apollo 13 ship would simply adhere to its uniform motion tangent to its original path. Another group of scenes in which Newton’s First was displayed was when the astronauts moved around in their spacecraft while in space.

It is quite easy to tell from watching how the astronauts moved around in 0g that they were exhibiting Newton’s First Law. If an astronaut in the movie applied a force in one direction to move in the other that astronaut would then move at a constant velocity (in relation to the ship) as soon as that force was removed. On the contrary, if no force were applied, the astronaut would remain at rest in relation to the ship. Overall, Newton’s First Law was shown in Apollo 13 when the astronauts moved around in their spacecraft and when the spacecraft traveled through space.

The third law that was very important in Apollo 13 was Newton’s Third Law which states to every action there is an equal and opposite reaction. The first main scene in which Newton’s Third Law was demonstrated was when the Apollo 13 crew had to execute a burn. By firing the main engine, they released gas particles into space, therefore applying an equal and opposite force on the ship. The burn was used to break free of the Earth’s gravity and to adjust the spacecraft’s trajectory slightly in order to make it home.

Another main scene in which Newton’s Third Law was displayed was when the astronauts were in space, and they needed to move around in their spacecraft. In order to move, the astronauts had to apply a force in one direction in order to have a reaction force applied on them in the opposite direction. In 0g the astronauts could use their hands to push on other surfaces and move them in the opposite direction. The third main scene in which Newton’s Third Law was demonstrated was when the Apollo 13 spacecraft ejected small amounts of gases to adjust the trajectory of the ship by fine amounts.

By ejecting small amounts of gases the ship was exerting a force in one direction and receiving an equal force in an opposite direction, and therefore changing its path. By releasing just the right amount of gases the spacecraft could change its trajectory to make it home safely. Looking at the whole, Newton’s Third Law was exhibited by the spacecraft when it ejected gas particles into space, when it executed a burn, and when the astronauts moved around in their spacecraft. Many laws of physics were used in the movie Apollo 13.

These laws helped to enforce the realistic feeling that this movie gave to its viewers. Not only were Newton’s Laws included but others were also used in smaller quantities, including Kepler’s laws and kinematic equations. Ultimately, the three commonly used laws in Apollo 13 were Newton’s First Law, Newton’s Third Law, and Newton’s Law of Universal Gravitation.

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