Zero Gravity: Apollo 13

What is weightlessness?

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The concept of being weightless is a tricky subject. Many misconceptions can alter someones perception of the topic. One misconception being that weightlessness is the lack of weight. This is wrong because in physics we see weight as the normal force acting on an object (the force the ground is exerting against the object), meaning unless there is literally no gravity, an object is technically not "weightless". This means the only way an object could experience weightlessness is if the acceleration of an object and the the affect of gravity on the object are 0. Meaning an object in free fall is technically experiencing weightlessness which inadvertently shows how astronauts on space stations are technically in constant free fall towards the planets they are orbiting. 

Using Newtons 2nd Law we can conceptualize this with the gravity constant close to earth.

 Î£F=ma

N - mg = m(-9.8m/s^2)

N = m(9.8m/s^2) - m(9.8m/s^2)

N = 0
 
We can see this equation in action in Apollo 13 through the application of a giant plane and a special flying pattern. The plane is the KC 135 and it flies in a parabolic pattern ascending and descending rapidly to effectively make a person feel "weightless". In the descension of the plane it eliminates the normal force of the plane on the person and puts the person into free fall displaying the effects of "weightlessness". With an incredible set built into the special plane the directors of Apollo 13 were able to get a realistic representation of weightlessness in space. 



Using the ISMP movie rating system I give this movie a GP because the space physics in the movie are great.
 

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