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Unformatted text preview: homework 01 KERR, KELSEY Due: Jan 18 2008, 11:00 pm 1 Question 1, chap 1, sect 1. part 1 of 2 10 points The rectangular and polar coordinates of a point are ( x, y ) and ( r, ), where x = 9 and = 56 . Determine the value of r. Correct answer: 16 . 0946 (tolerance 1 %). Explanation: The relation between rectangular and polar coordinates is: x = r cos y = r sin solving for r, r = x cos and y = r sin = x sin cos Question 2, chap 1, sect 1. part 2 of 2 10 points Determine the value of y. Correct answer: 13 . 3431 (tolerance 1 %). Explanation: Question 3, chap 1, sect 4. part 1 of 3 10 points Are all molecules of a particular substance alike? 1. No 2. Yes correct Explanation: Molecules are the smallest division that a substance can be divided into without chang ing its physical properties. Molecules are alike in their makeup and shape. They can bend slightly and flex, but always around a standard. Question 4, chap 1, sect 4. part 2 of 3 10 points Can molecules be broken into parts? 1. No 2. Yes correct Explanation: Molecules are clumps of atoms. In chemical reactions molecules can rearrange and break apart. Question 5, chap 1, sect 4. part 3 of 3 10 points How big are molecules? 1. around 10 6 meters in scale 2. around 10 2 meters in scale 3. around 10 2 meters in scale 4. around 10 10 meters in scale correct Explanation: The size of molecules are highly depen dent on the molecule. The smallest molecules are 10 10 meters in scale, and almost all are smaller than 10 6 meters in any dimension. Question 6, chap 1, sect 6. part 1 of 2 0 points The Statue of Liberty weighs nearly 205 tons. If a person can pull an average of 90 kg / person, how many people would it take to move the Statue of Liberty? Correct answer: 2278 (tolerance 1 %). Explanation: Let : w = 205 tons and R = 90 kg / person . Apply dimensional analysis: 205 tons 90 kg / person 1000 kg 1 ton = 2278 people . homework 01 KERR, KELSEY Due: Jan 18 2008, 11:00 pm 2 Question 7, chap 1, sect 6. part 2 of 2 10 points The weight of the space shuttle is about 4 . 5 million pounds. How many people would it take to move it? Correct answer: 22728 (tolerance 1 %). Explanation: Let : w = 4 . 5 10 6 lb . 4 . 5 10 6 lb 90 kg / person 1 kg 2 . 2 lb 1 90 kg / person = 22728 people . So it would take about 22728 people to move the Statue of Liberty. Question 8, chap 1, sect 6. part 1 of 1 10 points Identify the equation below which is dimen sionally incorrect . A, x, y and r have units of length. k here has units of inverse length. v and v have units of velocity. a and g have units of acceleration....
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 Spring '08
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