By:: Maverick Raymundo
Weightlessness In Space
1995 :: Apollo 13 (GP)
In the recent featured adaptation, Apollo 13 was a classic movie I enjoyed watching. The whole presentation was an awesome portrayal of the actual tribulation of a failed mission. It was a suspenseful movie since every step of cooperation was critical in bringing the astronauts home safely. The movie was minimal in the flow of the story and emphasize bringing life and awareness of the rescue mission. Prior to watching the movie I did not have any knowledge about this particular space expedition. After researching some information about the actual Apollo 13 held in 1970, I was surprised about the accurate mishaps of the whole situation and did not modify anything to gain profit. I thought that both actors and astronauts looked alike along with the damaged service module. I praise the brave astronauts for being composed and although they did not accomplish their lunar landing, they were the qualified men to handle an emergency as dire as this. America has learned a design flaw in the oxygen tank that nearly made this mission a disaster in history.
To recreate the fundamentals of the physics of being in space, the whole movie crew had to simulate the "zero gravity" effect on a plane in a parabola trajectory over 200 times. The main intention of doing this is to eliminate the normal force to overall feel lighter by putting everyone inside in freefall. Free fall is any motion of a body where gravity is the only acceleration acting upon it. Mass is conserved yet there is nothing pushing up against the object thus making it weightless. The normal force is described as contact force between objects always pointing perpendicular to their surface. We perceive weight through the normal force of Earth's surface. The normal force is what supports the object from falling through the surface it contacts with; it is always equal in magnitude and opposite in direction. The gravity near Earth's surface (acceleration due to gravity) will always be 9.8 m/s^2 for all objects. In addition to this, Newton's 2nd law states that each object experience different force of gravity proportional to their mass (F=ma).
Fg=Gm1m2/r^2
The attraction of gravity cannot be truly zero since the radius between two masses will never be infinitely apart. Some misconception people typically have of space is that the force of gravity is manipulated/decreased which is not the case. An object can only experience 0 Newtons of normal force if the object is in freefall (mid-air/constant acceleration due to gravity) or Fg=0. Astronauts in the ISS orbiting Earth are feeling "weightless" because they are in constant freefall where there is a lack of normal force present. In addition, the ISS in orbital motion, is going at the right speed where their velocity cancels the pull of gravity; basically a projectile motion (freefall) but in a path that will never hit Earth. This is due since the force of gravity has a small influence when they are above 300,000 meters high (bigger radius). They would undergo this path forever as backed by Newton's 1st Law. If this speed (around 7,700 m/s) were any less or more then it would not achieve uniform circular motion because their centripetal force would be not enough or greater than gravity. Any other objects that are not in orbit would travel to the center of the planet. Just as if you were in an elevator and its cables unfortunately snapped, you would feel weightless because there is no normal force acting on you since the elevator is also in freefall and the only force acting is gravity. To calculate the normal force you would use Newton's 2nd law (F=ma) and see that the force of gravity cancels out your mass and acceleration resulting in feeling weightless in a short span of time before hitting the ground.
Fg=Gm1m2/r^2
The attraction of gravity cannot be truly zero since the radius between two masses will never be infinitely apart. Some misconception people typically have of space is that the force of gravity is manipulated/decreased which is not the case. An object can only experience 0 Newtons of normal force if the object is in freefall (mid-air/constant acceleration due to gravity) or Fg=0. Astronauts in the ISS orbiting Earth are feeling "weightless" because they are in constant freefall where there is a lack of normal force present. In addition, the ISS in orbital motion, is going at the right speed where their velocity cancels the pull of gravity; basically a projectile motion (freefall) but in a path that will never hit Earth. This is due since the force of gravity has a small influence when they are above 300,000 meters high (bigger radius). They would undergo this path forever as backed by Newton's 1st Law. If this speed (around 7,700 m/s) were any less or more then it would not achieve uniform circular motion because their centripetal force would be not enough or greater than gravity. Any other objects that are not in orbit would travel to the center of the planet. Just as if you were in an elevator and its cables unfortunately snapped, you would feel weightless because there is no normal force acting on you since the elevator is also in freefall and the only force acting is gravity. To calculate the normal force you would use Newton's 2nd law (F=ma) and see that the force of gravity cancels out your mass and acceleration resulting in feeling weightless in a short span of time before hitting the ground.
Overall I considered the movie was well constructed in replicating the motions in space without using generated effects or strings. The progression of science advancement provided confidence for future missions and potentiality for more discovery in the betterment of humankind.
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