有一個波,向上拋之後落返黎,take upward is postive
咁點解個acceleration 會係-10 ?
唔係向上拋唔係應該+10,趺返落黎先係-10 咩?
t/s s/m v/ms^-1 a/ms^-2 t/s s/m v/ms^-1 a/ms^-2
3 45 0 -10 O
2 40 10 -10 O O 4 40 -10 -10
1 25 20 -10 O O 5 25 -20 -10
0 0 30 -10 O O 6 0 -30 -10
有d physics唔係好明....
2008-04-08 1:21 am
回答 (3)
2008-04-08 8:54 am
✔ 最佳答案
哈!!呢個問題我係半年前都問過果陣我都唔係好明
例如你向上為正~但重力係下面麻so係-10a/m-2
當你落下時~又係向下so係10a/m-2
你let向上係 -既話 情況就相反番
其實無論你let 上係 +/- 答案都係一樣...
2008-04-08 2:18 am
因為重力既方向一直係向下,所以acceleration一直都係-10
不過個波跌落黎果陣個velocity都係負數,所以先抵消左負號。
2008-04-10 15:35:12 補充：
所以並唔係向下果陣acceleration係+10.
2008-04-10 15:36:31 補充：
這是一般人常犯的concept,我以前也錯過。
不過個波跌落黎果陣個velocity都係負數,所以先抵消左負號。
2008-04-10 15:35:12 補充：
所以並唔係向下果陣acceleration係+10.
2008-04-10 15:36:31 補充：
這是一般人常犯的concept,我以前也錯過。
參考: , 自己
2008-04-08 1:50 am
有一個波,向上拋之後落返黎,take upward is postive
咁點解個acceleration 會係-10 ?
It is -10 becasue the acceleration caused by gravitation is acting downwards.
咁點解個acceleration 會係-10 ?
It is -10 becasue the acceleration caused by gravitation is acting downwards.
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