quiz 既mc題 =[

sapphire

原帖由 小霞的fans 於 12/12/2008 06:19 PM 發表


咁我如果take downward direction of ballA 係positive
咁佢既a 就-10^-2 因為佢向上升
咁我take downward direction of ball B 係 positive
咁佢既a咪係10^2 囉 ..因為佢向下跌

咁2個既acceleration咪唔 ...

Direction is defined when you start to do a question, NOT for each object = =|||
I have said before, NO MATTER the object is moving up or moving down, its acceleration due to gravity is ALWAYS towards the ground.
NOT related to "佢向上升" or "佢向下跌"

[ 本帖最後由 sapphire 於 12/12/2008 06:32 PM 編輯 ]

鴨

原帖由 小霞的fans 於 12/12/2008 06:19 PM 發表


咁我如果take downward direction of ballA 係positive
咁佢既a 就-10^-2 因為佢向上升
咁我take downward direction of ball B 係 positive
咁佢既a咪係10^2 囉 ..因為佢向下跌

咁2個既acceleration咪唔 ...

不...
它們兩個的a也是向著地面10ms-1
就算define了不同方向是正...
所得出的結果也同樣是向著地面的方向10ms-1...
所有的東西關注的是方向而不是單純的正負...

abc666

對不起...不知為什麼看錯問題,竟然看多了「same initial postion」...