[考古] 臺聯大今年一題

看板trans_math作者 (普萊亞)時間11年前 (2013/07/21 21:04), 編輯推噓2(2推 0噓 2→)
留言4則, 2人參與, 最新討論串1/1
The coordinates of a particle in the xy-plane are differentiable functions of time t with dx/dt= -1 m/sec and dy/dt= -5 m/sec. How fast is particle's distance form the origin changing as it pass through the point (5, 12)? 懇請解答<(_ _)> -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 59.104.29.186
推
07/21 21:14, , 1F
總覺得是不是少條件了?
07/21 21:14, 1F
推
07/21 21:25, , 2F
轉學版有人給答案了d/dt (x^2+y^2)^1/2
07/21 21:25, 2F
→
07/21 21:26, , 3F
然後代入dx/dt=-1 dy/dt=-5 (x,y)=(5,12)
07/21 21:26, 3F
→
07/21 21:27, , 4F
可以得到答案為-5
07/21 21:27, 4F
‣ 更多 tn00330905 的文章
文章代碼(AID): #1HwzniNv (trans_math)