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物理 高中

(第一張照片)守恆的概念是沒問題的,但換符號好像有點問題,mg是怎麼換成mV/r的???還有a是怎麼換成V^2/r的???感覺是我前面換算學得不太好的關係🥺 (第二張照片)想知道c選項的算式是怎麼來的?

範例3 圓周運動的力學能守恆 雲飛車是一種常見於主題樂園中的遊樂設施, ao 其軌道通常有如圖所示的迴圈。若考慮正圓的迴 圈軌道,且軌道可視為在一鉛直面上,雲霄飛車 的車廂在沒有動力驅動之下,沿著軌道內側繞行, 且軌道只能提供向心力,摩擦阻力可忽略,重力 加速度為g,則當車廂可沿整個圓圈軌道繞行時,車廂在軌道最低點的加速度量值至少 為何? (A) 2g (B) 3g (C) 4g (D) 5g (E) 6g 向心力: V₁ F=mg= m JJR VH R + a₁ = JEJR (JSJR) R V₁ R 1=5g A.0) 願選一條長為R的繩子綁住一個石塊,讓石塊一開始在鉛直面上作圓周運 動,石塊的位置可由石塊—圓心連線和水平線夾角表示,如右圖所 Mo 示。若石塊在最低處的速率改為 7gR g為重力加速度,則石塊轉 2 到何處時會脫離如圖所示之圓形虛線軌跡?(已知sin37°=0.6) (A)=30° (B)=37° (C)=45°(D)=53°E=60° R my mg cose 79R 2 ① 力学能守恆 /m() :/mv+mgal1+sine) myR 2 → v² 1 gk (3-4 sino) ② 圓周運動(向心力:張力、動) T+ mg sino - V = 1mg (3-4 sino) →繩鬆⇒7:0 →脫離:與最低點高度差h " R+R Sind ⇒ 0+mg sine = 1 mg (3-45/40> : R(1+ Sine) => sino 0-300 【107. 指考】

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英文 高中

求解第2、7題

10% Can money buy happiness? People have always wondered 1. money really makes them happy. Researchers used to believe that it is up to a certain point happiness increases with income: beyond an annual income of $75,000, people are no happier with higher salaries. 3., recent studies have indicated that happiness still increases when salaries are higher than $75,000. The main reason that money seems to bring happiness is 4. more money can bring greater financial security. Daily activities such as grocery shopping are easier when most of the anxiety regarding what 5. is removed. In this way, money could be viewed as a solution problems. 6. one's on individual Most studies related to this question are based on averages rather than experiences. 7., there are many exceptions to the rule that happiness increases with 8. making $25,000 per year. By contrast, one's income. Some people are satisfied others feel that millions of dollars are required 9. their desired lifestyles. Compared with averages, the individual items that people spend their money on may be truer measures of happiness. A few studies have indicated that people are happy 10. they spend their money on specific items. This suggests that although having all the money in the world may not make you happy, it would give you more choices in purchasing the items you want. Such choices could surely increase one's happiness. anw spalliv siff (D) whether ) 1.(A) where (B) who (C) what (A) 2)(A) that (B) when (E) how (D) which (A) 3.(A) However (B) Thus (C) Similarly (D) Moreover (C) 4.(A) who (B) why (C) that (D) where B) 5. (A) can one afford (B) one can afford (C) does one afford (D) can afford one 6. (A) to (B) with (C) for (D) in 7.(A) Finally (B) In addition (C) Therefore (D) For example 8.(A) on (B) to (C) by (D) with

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