物理問題:花生落地的力度一樣嗎???

你e個問題,真係要做過實驗才知道
因為樓上都講得岩,無人真係測試過花生既終極速度係幾多
亦唔知道2000米既距離足唔足夠讓花生下墮至終極速度
而且既然你要連空氣阻力都計算在內的話,這個問題就會變得複雜很多
會加入很多不可預計的變數在內....

雖然兩粒花生是同質量同重量,但他們的形狀可以不一樣...表面面積也不同,下墮時和空氣接觸產生磨擦的面積也是不同,這都會對空氣阻力有影響,而改變終極速度

正同,一支100kg的鐵針在100米高的地方垂直地,自由落體,掉去地面
和一塊100kg很長很闊的鐵塊在150米高的地方,以平面自由落體掉去地面,兩者的空氣阻力和終極速度都會有所不同,咁你話，兩者邊個落力果下力會大d ?

好啦，就算你連形狀也是一樣，和空氣接觸磨擦的表面面積也是一樣
但係到底果粒花生，有冇機會達到地面，都是一個未知之數....,

相信很多人都知道，其實每年都有好多外太空隕星撞落地球，但係未到達地面之前
就與大氣層產生磨擦，不斷燃燒和磨損，而成粒燒盡
咁粒花生都可能同樣原理，佢在高空，以咁高既速度，咁長既距離，去不斷與空氣產生磨擦，成粒燒到變灰都話唔埋．．．咁佢連落地既機會都無，重講咩力度既大細呢?

所以如果以你咁講，其實真係無一個可以肯定既答案，因為當中包括著既變數實在太多太大,如果你要忽略哂其他所有既變數，單憑只理會[終極速度]黎支持自己既講法，咁係無意思，因為你可以忽略其他因數計出這個答案，別人也可以忽略你的[極終速度]來計算另一個答案．大家的觀點，角度，計算數據都不同，說誰對誰錯，都是無意思

p.s.在同一碟抄飯中，你說因為碟飯落左鹽夠咸所以好好食，你的朋友說，碟飯太多油唔好食，咁到底碟飯好唔好食呢??大家既角度都唔同，點可以話對方既說話錯?

一物體下跌時的重力是不變
但空氣阻力與物體的速度成正比
當ｂ＝ｆｖ時物體速度不變
但花生落地的ｄ不知足不足夠終端速度
因為空氣阻力正比於面積
而花生面積少３０００ｍ可能都在加速

你與你同事都對，地球有向心加速度，越高下降，到達地面時就越高速。你之意見是任何自由落體都有終極速度，而這終極速度是受物體本身形狀影響，一般自由落體之終極速度不會超過音速(除了炮彈或子彈，因它們之初速已近音速)。事實無人計算過花生之空氣阻力，所以亦無從計算花生之終極速度，但以跳傘人士來比較，他們要6-7000尺就可達到終極速度。所以我會說你們都正確。

我只可以答你佢地個 weight 都係一樣
但係墜地的velociy 係唔同 而且要考慮 momentum 但係我未教
If an object is moving in any reference frame, then it has momentum in that frame. It is important to note that momentum is frame dependent. That is, the same object may have a certain momentum in one frame of reference, but a different amount in another frame. For example, a moving object has momentum in a reference frame fixed to a spot on the ground, while at the same time having 0 momentum in a reference frame attached to the object's center of mass.

The amount of momentum that an object has depends on two physical quantities: the mass and the velocity of the moving object in the frame of reference. In physics, the symbol for momentum is usually denoted by a small bold p (bold because it is a vector); so this can be written:


where:

p is the momentum
m is the mass
v the velocity
(using bold text for vectors).

The origin of the use of p for momentum is unclear. It has been suggested that, since m had already been used for "mass", the p may be derived from the Latin petere ("to go") or from "progress" (a term used by Leibniz).[citation needed]

The velocity of an object at a particular instant is given by its speed and the direction of its motion at that instant. Because momentum depends on and includes the physical quantity of velocity, it too has a magnitude and a direction and is a vector quantity. For example the momentum of a 5-kg bowling ball would have to be described by the statement that it was moving westward at 2 m/s. It is insufficient to say that the ball has 10 kg m/s of momentum because momentum is not fully described unless its direction is given.
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