Which of the following kinds of motion is/are possible in one particular instant?
(1) Moving with constant speed but non-zero acceleration
(2) Mving with zero-velocity but non-zero acceleration
(3)Moving with constant velocity but non-zero acceleration
A (1)only
B (3)only
C (1) and (2)only
D (2) and (3) only
個答案好似是c....
可不可以解釋點解是c...
(最好舉例)...thx
phy mc...
2006-12-12 12:15 am
回答 (2)
2006-12-12 12:25 am
(1) 講緊既係speed..係 scaler ，而accleration 係vector
所以 (1)係可行既.. 當佢轉方向但係speed 依然一樣既話..
咁就會有constant speed , but non-zero acceleration
(2) 當物體由 -ve velocity 加速至 +ve velocity..
中途係會經歷到 zero-velocity個點.. 但係依然有accleration
就好似一件物件向上拋，去到最高點咁
(3) 是不可行的..
因為 velocity 是vector.. 而accleration亦係vector
從v-t graph 既slope可以睇.. constant velocity既slope (acceleration) 一定係zero
所以 (1)係可行既.. 當佢轉方向但係speed 依然一樣既話..
咁就會有constant speed , but non-zero acceleration
(2) 當物體由 -ve velocity 加速至 +ve velocity..
中途係會經歷到 zero-velocity個點.. 但係依然有accleration
就好似一件物件向上拋，去到最高點咁
(3) 是不可行的..
因為 velocity 是vector.. 而accleration亦係vector
從v-t graph 既slope可以睇.. constant velocity既slope (acceleration) 一定係zero
參考: 自己
2006-12-12 12:23 am
1. circular motion 中，speed 可以保持不變，但 acceleration 指向圓心
2. simple harmonic motion 的中間點，velocity = 0，acceleration 最大
3. 違反定義 a=dv/dt
2. simple harmonic motion 的中間點，velocity = 0，acceleration 最大
3. 違反定義 a=dv/dt
收錄日期: 2021-04-13 13:27:19
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20061211000051KK01955