牛津定律(十分容易)

第一，這不是牛津定律，是牛頓定律。
第二，因為地球的萬有引力大於月球的6倍，所以不會。

answer 1, 2, 4 是錯的。
answer 5 係 A-Level 程度答案，
answer 3 係 大學本科程度的答案。

answer 3 的意思係：蘋果本身無[橫向動作],所以好明顯直落；
而月球本身有橫向的慣性，加上地球作用在其身上的引力，會導致一個 curved path 曲向的運動路線，
而這個運動路線，同地球的表面曲度剛好一樣，所以像在圍著地球轉。

answer 5 只考慮到 centripedal force, 忽略左個 initiation.

根據Newton's law of gravitational, F=GMm/r^2
蘋果, 月球, 地球都有mass, 所以蘋果同月球都受到地球ge重力

月球唔會衝向地球係因為佢不停圍住地球轉
月球ge circular motion需要有centripetal force(向心力)
而centripetal force ge來源就係地球ge重力

由於地球ge重力被月球用作uniform circular motion, 所以唔會衝向地球

當你係月球上放下蘋果 佢都係跌番落地面 因為月球都有引力 你諗諗 如果 月球冇引力 點解太空人可以係月球漫步呢?

In the actual fact, the moon is constantly [falling] toward the earth.

Because of gravity exerted on the moon by the earth, the moon is being pulled to fall towards the earth. But the moon is in motion and has already acquired a certain velocity (just contrast to the apple example, the apple has no velocity initially relative to the earth), the result of the pullling force by gravity and the initial velocity makes the moon to fall in a curved path, similar to the path traversed by a throwing stone in air.

It so happens that the curvature of the falling path of the moon matches exactly with the curvature of the spherical earth. Because the two curvatures are in parall, the consequence is that the moon could never fall to reach the earth surface, instead it maintains at a constant distance from the earth during its falling.

因為地球的引力是月球引力的六倍
因此在月球蘋果的重量只有六份一,,輕左好多
地心吸力少左所以冇咁易掉下來~