#shuttle
Check out a previous post on gravity here, and another post on planetary orbit here.
Gravity and Astronauts in Orbit
Newton’s Law of Gravity states that the gravitational force between any two objects in the universe is proportional to the mass of the objects and inversely proportional to the square of the distance (measured from their centers) between them. That means that if you double the size of either of the masses, the gravitational force will double. Then also if you halve the distance between the two objects and their masses stay the same, the gravitational force between them will quadruple. The converse of both these statements is also true.
Despite gravity keeping everything around you steadily on the ground, it’s considered to be the weakest force in relation to the other four fundamental forces. After all, you can easily overcome the gravitational force of the whole entire Earth for a few seconds by simply jumping or throwing a ball up into the air.
A common misconception is that there’s no gravity in outer space. Anything with mass has an infinitely large gravitational field - but because it gets progressively weaker with distance, its effects quickly become negligible.
Then why do astronauts float around in the space shuttle? Why are they weightless? The only reason you can feel your weight on Earth is because the Earth is pushing back up at you. It’s the normal force from the Earth on your body. However within an orbiting spacecraft, you’re in free fall. There’s nothing to push back at you and make you feel your weight!
Fun fact: Astronauts experience a lot of nausea and headaches during their first few weeks in orbit. This is probably because not only are they in free fall, but the liquids inside them are probably flowing around too (eg. fluids to the brain, nasal cavities, stomach contents, etc…)
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前排nasa第二次試左佢個上火星既新火箭噴射引擎
令我諗返呢個我之前寫低既Apollo 1 同宇宙兄弟既一句對白
係1967，本來Apollo 1會係2月21號發射
但係1月27號，三個太空人都係基地入面一個演習時燒死左
分別係Command Pilot Virgil I. Grissom, Senior Pilot Edward H. White II, Pilot Roger B. Chaffee
係1968年，經過21個月既調查同修改，Apollo 7係10月11號再發射，完成Apollo 1既任務
: ) 那一天，夢想隕落了，讓勇氣再一次發射升空
over and out
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