acceleraion問題 =___=

小霞的fans

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 - ?

sapphire

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

小霞的fans

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. ..

Royal

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)

[UP]Insulator

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

luigiluigi1113

acceleration係vector嗎
+ve 向前加速
0     靜止or速度冇變
-ve  向後加速

Ivanhy92

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.