Question about this picture....? plz help..ty?

2009-03-17 4:32 am

http://img18.imageshack.us/img18/7635/50877234.jpg
The ball stop at 15m, i want to know how fast is the ball at the black circle, (just before the ball hit the ground) the friction force of the ground is 320N
If you could explain ,ty :)

更新1:

Hi, i want to know what force is acting on it, (not the friction force) when the ball is moving i am confused, like when the ball is moving ,what type of force is acting on it to push the ball forward?(starting from the black circle)

回答 (1)

[匿名]

2009-03-17 5:22 am

✔ 最佳答案

Assuming that the ball is moving with constant acceleration, starting from the black circle, and the only force against it is the friction of 320N of the ground.

Using F = ma
-320 = 75 a
a = -4.27 m/s^2

Initial velocity (at the black circle), u = ???
Final velocity, v = 0 m/s
Displacement, s = 15 m

Using v^2 = u^2 + 2as
u^2 = 128
so u = 11.3 m/s (ans)

👍 0 👎 0

收錄日期: 2021-04-28 23:58:15
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090316203210AAsrYRx

檢視 Wayback Machine 備份