this tendency of bodies to move towaed one another is called gravitation, and the "stuff" that is involved is the mass of each body. if the myth were true then the attraction is between the mass of the apple and the mass of earth. it is appreciable because the mass of Earth is so large, but even then it is only about 0.8N. the attraction between two people standing near each other on a bus is (thankfully) much less(less than 1uN) and inperceptible.

the grevitational attraction between extended objects such as two people can be difficult to calculate. here we shall focus on newton's force law between two paricle (which have no size). Let the masses be m1 and m2 and r be their separation. then the magnitude of the gravitational force acting on each due to the presence of the other is givn by



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결국엔 이런책 사진 찍어서 올렸는데..


에휴..


재는 r이 뭔지.. 만유인이 뭔지... 중력이 뭔지도 모르는듯..


그냥 그렇게 살고 내 인생에 끼지 말아라..


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