derivative

Sec.4.7 - 飛機和鳥:能量最小化

Applied Project 2 in Sec.4.7, Calculus by Stewart 英文版請見 Planes and birds: Minimizing energy 像雀科這樣的小鳥滑翔時,會在拍打翅膀和保持翅膀折疊之間進行交替。在這裡,我們觀察這種現象並試著找出鳥類拍

Sec.8.3 - Complementary Coffee Cups

Applied Project in Sec.8.3, Calculus by Stewart Chinese version: Complementary Coffee Cups Suppose you have a choice of two coffee cups of the type shown, one that bends outward and one inward, and you notice that they have the same height and their shapes fit together snugly. You wonder which cup holds more coffee. Of corse you could fill one cup with water and pour it into the other one

Sec.3.1 - Building a better roller coaster

Applied Project in Sec.3.1, Calculus by Stewart Chinese version: 建造較佳的雲霄飛車 Suppose you are asked to design the first ascent and drop for a new roller coaster. By studying the photographs of your favorite coasters, you decide to make the slope of the ascent $0.8$ and the slope of the drops $-1.6$. You decide to connect these two straight stretches $y=L_1(x)$ and $y=L_2(x)$

Sec.4.7 - 罐頭的形狀

Applied Project 1 in Sec.4.7, Calculus by Stewart 英文版請見 The shape of a can 給定一個體積為 $v$ 的圓柱體罐頭,我們想找到一個高 $h$ 和半徑 $r$ ,將製成罐頭的金屬量減到最小。 如果我們將製程中金

Sec.3.4 - 飛行員應該何時開始下降高度?

Applied Project in Sec.3.4, Calculus by Stewart 英文版請見 Where should a pilot start descent? 上圖是一台飛行器的降落軌跡近似圖,它必須滿足以下條件: 巡航高度為$h$,而飛行器在與著陸地點(同時也是圖

Sec.4.7 - Planes and birds: Minimizing energy

Applied Project 2 in Sec.4.7, Calculus by Stewart Chinese version: 飛機和鳥:能量最小化 Small birds like finches alternate between flapping their wings and keeping them folded while gliding. In this project we analyze this phenomenon and try to determine how frequently a bird should flap its wings. Some of the principles are the same as for fixed-wing aircraft and so we begin by

Sec.4.7 - The shape of a can

Applied Project 1 in Sec.4.7, Calculus by Stewart Chinese version: 罐頭的形狀 Given a cylindrical can with fixed volume $v$, we want to find the height $h$ and radius $r$ that minimize the cost of metal to make the can. If we disregard any waste metal in the manufacturing process, then the problem is to minimize the surface area of the cylinder. It can be found that

Sec.3.4 - Where should a pilot start descent?

Applied Project in Sec.3.4, Calculus by Stewart Chinese version: 飛行員應該何時開始下降高度? An approach path for an aircraft landing is shown in the figure and satisfies the following conditions: (i) The cruising altitude is $h$ when descent starts at a horizontal distance $\ell$ from touchdown at the origin. (ii) The pilot must maintain a constant horizontal speed $v$ throughout

用電腦算微分

前情提要: 用電腦算極限 這裡我們要講的是用數值計算來算函數的微分值. 已知一個函數 $f(x)$ 在某個點 $a$ 的微分值定義是 $$ f'(a) = \lim_{h\to 0} \frac{f(a+h)-f(a)}{h}. $$ 我們用一個簡單的例子試