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自然科學 大學

想問3-9的a跟c

Problems 3-1. Explain the difference between *(a) random and systematic error. (b) constant and proportional error. *(c) absolute and relative error. (d) mean and median. *3-2. Suggest two sources of systematic error and two sources of random error in measuring the length of a 3-m table with a 1-m metal rule. 3-3. Name three types of systematic errors. *3-4. Describe at least three systematic errors that might occur while weighing a solid on an analytical balance. *3-5. Describe at least three ways in which a systematic error might occur while using a pipet to transfer a known volume of liquid. 3-6. Describe how systematic method errors may be detected. *3-7. What kind of systematic errors are detected by varying the sample size? 3-8. A method of analysis yields masses of gold that are low by 0.4 mg. Calculate the percent relative error caused by this result if the mass of gold in the sample is (a) 500 mg. (b) 250 mg. V(c) 125 mg. (d) 60 mg. 3-9. The method described in Problem 3-8 is to be used for the analysis of ores that assay about 1.2% gold. What minimum sample mass should be taken if the relative érror resulting from a 0.4-mg loss is not to exceed *(a) -0.1%? (b) -0.4%? (c) -0.8%? (d) - 1.1%? 3-10. The color change of a chemical indicator requires an overtitration of 0.03 mL. Calculate the error if the total volume of titrant is percent relative (a) 50.00 mL. (c) 25.0 mL. 3-11. A loss of 0.4 mg of Zn occurs in the course of an percent relative analysis for that element. Calculate the error due to this loss if the mass of Zn in the sample is *(b) 10.0 mL. (d) 30.0 mL. 190 (c) 188 (d) 4.52 x 103 4.63 x 103 4.53 x 10 ³ √6 *(a) 30 mg. (b) 100 mg. *(c) 300 mg. (d) 500 mg. 3-12. Find the mean and median of each of the following sets of data. Determine the deviation from the mean for each data point within the sets, and find the mean devi- Vation for each set. Use a spreadsheet if it is convenient. *(a) 0.0110 0.0105 (b) 24.53 0.0104 24.68 24.81 24.77 39.61 862 (f) 850 MA 3-13. Challenge Problem: Richards and W the molar mass of lithium and colle data. 24.73 Experiment 1 2 3 4 5 6 194 447 X 10 7 448 X 107 4.58 X 10 (a) Find the mean molar t workers. (b) Find the median molar ma (c) Assuming that the cam molar mass of lithium is the absolute ertor and of the mean value demi Willard. (d) Find in the chemical ues for the molar mus since 1910, and ag a table or spreadshera 1817 given in the a Richards and Willd. Com mass versus year to la of lithium has chang Suggest possible abruptly about 18 ant de (e) The incredibly deals Richards and W that major changes will occur. Disc calculation in pat (f) What factors ha since 1910? (g) How would you mass? 6See Chapter 2 of Applications of Microsoft Excel in Analytical Chemistry, 4th ed., for information about statistical 7T. W. Richards and H. H. Willard, J. Am. Chem. Soc., 1910, 32, 4, DOI: 10.1021/ja01919a002. built-in statistical functions. "Answers are provided at the end of the book for questions and problems marked with an asterisk The I of ₂ or inc rce of able vas error c often in individu ate resul data in rtainties. dimensio andom e analysts The result

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自然科學 大學

請問第9題的第四小題,為何B選項1:2:3:4不是正確的答案呢! 我個人認為B及D選項都是正確的! 請高手說明,謝謝!

關係圖(a-t圖)應為下列何者? (A) a (m/s) (B) 0 a (m/s) f(s) (C) ( )(1)連續兩影像間的時間間隔為何? (A)0.01秒(B)0.1秒(C) 1 秒(D) 10 秒。 ( )(2)物體落下時的平均加速度為多少 公分/秒?(A)87 (B) 870 (C)175 (D)1750。 ( )(3) x 值為何?(A)32 (B)35.5 (C) 39.3 (D) 42 • 答案:(1)(B);(2)(B);(3)(C) 13.1-4.4 解析:(2) =870(公分/秒) 0.12 [(x-17.5)-13.1] (3) =870,X- t(s) 0 a (m/s) (D) o 0 a(m/s?) t(s) 0 o 13610 0.12 393。 出處:試題 難易度:難 9. 請在閱讀下列敘述後,回答下列問題。 在義大利佛羅倫斯的科學史博物館成立 於西元1927年,經兩年翻修後於西元2010 年6月10日重新開館,更名為伽利略博物 館(Museo Galileo) 館內收藏了一座十八世紀後期的一個演 示儀器,長寬高為544cmx39cmx124cm,作 者不詳,在史上最美的十項科學實驗這本書 裡,作者克里斯(Crease)將此面稱為 Belled Plane。 此演示器材有兩組鈴鐺,第一組鈴鐺是 受懸掛在斜面後方的單擺牽動,每擺到最高 點時會敲響鈴鐺,並發出等時間間隔的鈴鐺 聲。第二組是斜面上5個活動鈴绪組,沿著 斜面設置,當球自高處滾下來經過鈴錯時, 就會發出聲音,演示者可以一邊聆聽單擺敲 出的鈴鐺聲,一邊排列這組活動鈴鐺,使球 滾下來敲響的鈴鐺聲也是等時間間隔的,以 測量各組活動鈴绪的間距比例是否符合「等 加速度」的特性。 ( )(1)當球自斜面高處滾下來的過程屬 於何種運動?(A)等速度運動 (B)等加速度運動 (C)加速度 運動 (D)自由落體運動。 ( )(2)球自斜面高處滾下的加速度-時間 f(s) ( )(3)球自高處滾下來經過鈴鐺時,敲 響的鈴鐺聲也是等時間間隔的意 義為何?(A)經過每鈴鐺的時 間間隔相同(B)鈴鐺間距相同 (C)鈴鐺發出的音高相同(D) 經過每鈴鐺的速度相同。 ( )(4)「等加速度」的特性是每隔相同 時間間格球移動的距離比應為下 列何者?(A)1:1:1:1( B) 1:2:3:4 (C) 1:4:9 : 16 (D)1:3:5:7。 答案:(1)(B);(2)(A);(3)(A);(4 (D) 出處:習作 難易度:難 10. 阿美費盡九牛二虎之力爬上高樓的樓頂, 正在欣賞美景時,不小心口袋中拾圓硬幣 掉出,自樓頂自由落下到地面需時4秒, 若不計空氣阻力(g=9.8 m/s),試回 答下列問題: ( )(1)硬幣著地的速度為多少?(A) 9.8 m/s (B) 19.6 m/s (C) 29.4 m/s (D)39.2 m/s。 ( )(2)阿美爬上多高的樓頂?(A) 78.4 m (B) 44.1 m (C) 29.4 m(D)19.6m。 16 1 4 q 17

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