mk asked in 科學及數學其他 - 科學 · 1 decade ago

gravitational & inertial mass

我想問 gravitational mass and inertial mass 有咩分別??

detail explainations plz!!!

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  • 1 decade ago
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    首先,mass有兩個定義:

    1. Gravitational mass

    2. Inertial mass

    兩者不同的地方,在於它們定義上的不同。好了,首先說gravitational mass。

    牛頓發現具有物質的物件,皆有一個互相吸引對方的特性。如果抄錄他在《原理》一書中的說明,就是:

    Every particle of matter in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of their distance apart.

    所說的,就是萬有引力定律 F = Gm1m2 / r2

    而inertial mass就是在動力學實驗中找出的物理量。是量度物件抗拒改變本身運動狀態的物理量。

    兩者在理論上是可以不一樣的,但是高準確度的實驗證明兩個mass的concept是一樣的(不是估計,not approximation),所以可以歸立為一個m表示。

    所以,當一件物件從高處墜下,mg = ma

    左邊的m是gravitational mass,而右邊的是inertial mass (牛頓第二定律)

    由於上面說了兩者是一樣的,所以在量值上(magnitude)

    a = g = 9.8 ms-2

    所以,我們當說地心加速度 = 9.8 ms-2

    Source(s): Physics king
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