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標題: acceleraion問題 =___= [打印本頁]

作者: 小霞的fans 時間: 26/10/2008 12:33 PM
標題: acceleraion問題 =___=
a=v-u/t

想問比左個a你 ..
我想知a幾會要變負數..
係佢slow down 先 - 定係方向唔係positive先 - ?

作者: sapphire 時間: 26/10/2008 01:06 PM
Acceleration is -ve when the speed of the object is decreasing, i.e. deceleration
However, when the object is accelerating but in the -ve direction, its acceleration is also -ve

作者: 小霞的fans 時間: 26/10/2008 01:21 PM

原帖由 sapphire 於 25/10/2008 05:06 PM 發表
Acceleration is -ve when the speed of the object is decreasing, i.e. deceleration
However, when the object is accelerating but in the -ve direction, its acceleration is also -ve

後面果句唔係好明. ..

作者: Royal 時間: 26/10/2008 01:55 PM
如果TAKE 右面係POSITIVE
A(加速度)負數既情況:
1) 向右面減速(v is less positive than u)
2) 向左面加速(v is more negative than u)

作者: [UP]Insulator 時間: 28/10/2008 09:27 PM

原帖由 小霞的fans 於 26/10/2008 01:21 PM 發表

後面果句唔係好明. ..

即係"倒後加速"

其實acceleration的 +/ - 是由方向決定的，向前就是正，向後就是負

作者: luigiluigi1113 時間: 31/10/2008 07:10 PM
acceleration係vector嗎
+ve 向前加速
0 靜止or速度冇變
-ve 向後加速

作者: Ivanhy92 時間: 28/12/2008 11:23 PM

原帖由 luigiluigi1113 於 31-10-2008 19:10 發表
acceleration係vector嗎
+ve 向前加速
0 靜止or速度冇變
-ve 向後加速

Yes...So beforehand stating positive/negative direction is needed.

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