拋體運動在科氏力下的修正

The correction of some projectile motions under Coriolis force

柳銘哲(Ming-Tse Liu)

《加馬》 49期 (2018/11) Pp. 17-27

摘要

這篇論文主要是用微分的方法將科氏力重新推導出來，然後在拋體離地球表面不遠、飛行時間不長的前提下，解決三個問題：首先是自由落體為什麼著地時會偏東；我們已經知道，當拋體上升時，其科氏力的方向與落下時相反，因此很多人認為拋體在垂直投擲後應該落回到原來的位置。事實上，它偏向西方，並且是一路偏向西方，而不是先向西，然後向東。我們解釋了為什麼會這樣，這是我們第二個解決的問題；最後是用慣性座標系解釋為什麼北半球的渦漩總是逆時針的。

關鍵字

科氏力 ； 地球自轉 ； 自由落體 ； 拋體 ； 數值計算

並列摘要

The main purpose of this paper is to re-deduce the Coriolis force by the differential method. Then we solve three problems on the premise that the projectile is not far from the surface of the earth and the flight time is not long. First, we explain why the free fall is biased eastward when landing; We have known that when the projectile rises, its direction of the Coriolis force is opposite to when falling, so many people think that the projectile should fall back to the original place after being vertical throwing. In fact, it is biased westward, and it is always biased westward all the way rather than first being westward then being eastward. We explain why this is so, which is our second point; The last is to explain why the vortex in the earth's northern hemisphere is always counterclockwise in the point of view of inertia coordinate system.

並列關鍵字

Coriolis force ； earth rotation ； free fall ； projectile ； numerical calculation