中二物理科問題一條

這是因為火箭的第一階段需要推進的第二和第三級火箭，飛船一起去了。有一個大的總質量，因此一大力量，更大的權力是必要的。

經過第一和第二級火箭燒毀，並拋出了，第三級火箭只需要推動飛船。因此群眾參與少得多。一個較小的力量，一個較小的功率就足夠了。

第三部分飛船在太空運行，但使用牛頓第一定律，它並不需要力量，使船舶回心房提出由於沒有任何空中，因此沒有任何摩擦。

the third park of the spaceship is operating at space,but using the newton's first law,it did not need the force to make the ship back anf forth since there's no any air,so there are no any friction.

It is because the first stage rocket needed to push the second and third stage rocket, together with the spacecraft to go up. There was a large total mass, hence a large force, and larger power was required.

After the first and second stage rockets burnt out and be thrown off, the third stage rocket only needed to push the spacecraft. The mass involved was thus much less. A smaller force, and a smaller power was sufficient.

因為要用較大動力以擺脫地球引力，當脫離地球勢力範圍時可改用較小動力，節省燃油。