Homework 3 - Solutions

# Homework 3 - Solutions - Maltese, James – Homework 3 –...

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Unformatted text preview: Maltese, James – Homework 3 – Due: Jan 30 2008, midnight – Inst: Angela Guzman 1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points Which of the following is a vector quantity? 1. mass 2. none of these correct 3. density 4. speed 5. temperature Explanation: A vector is a quantity with both magni- tude and direction. Temperature, density, and mass do not have direction, so they are scalars rather than vectors. Speed, by defini- tion, is the magnitude of velocity (which is a vector), so it is also a scalar. Therefore the correct choice is “none of these”. keywords: 002 (part 1 of 1) 10 points A person walks 25 m west and then 45 m at an angle of 60 ◦ north of east. What is the magnitude of the total dis- placement? 1. 26.5 m 2. 67.8 m 3. 45.7 m 4. 40.9 m 5. 31.0 m 6. 60.2 m 7. 43.6 m 8. 56.3 m 9. 39.1 m correct 10. 61.4 m Explanation: In a triangle with three sides of a, b, and c , if the angle between a and b is θ , then c 2 = a 2 + b 2- 2 ab cos θ . keywords: 003 (part 1 of 2) 10 points A B C D P R The vector ~ R shown in the sketch may be expressed in terms of ~ A , ~ B , ~ C , and ~ D , which are the edges of a parallelogram, as 1. ~ R = ~ C + ~ B . 2. ~ R = ~ B + ~ A . correct 3. ~ R = ~ B- ~ A . 4. ~ R = ~ A- ~ C . 5. ~ R = ~ C + ~ D . 6. ~ R = ~ A- ~ D . 7. ~ R = ~ A- ~ B . 8. ~ R = ~ B + ~ D . 9. ~ R = ~ A + ~ D . 10. ~ R = ~ D- ~ A . Explanation: The solution is found by the application of the parallelogram rule of addition; the tails of the two vectors ~ A and ~ B are joined together and the resultant vector is the diagonal of a parallelogram formed with ~ A and ~ B as two of its sides. Maltese, James – Homework 3 – Due: Jan 30 2008, midnight – Inst: Angela Guzman 2 004 (part 2 of 2) 10 points The vector ~ P shown in the sketch may be expressed in terms of ~ A , ~ B , ~ C , and ~ D as 1. ~ P = ~ A + ~ D . 2. ~ P = ~ D- ~ A . 3. ~ P = ~ B- ~ A . 4. ~ P = ~ B + ~ A . 5. ~ P = ~ C + ~ D . 6. ~ P = ~ C- ~ A . 7. ~ P = ~ C + ~ B . 8. ~ P = ~ B + ~ D . 9. ~ P = ~ A- ~ B . correct 10. ~ P = ~ A- ~ D . Explanation: By the triangle method of addition ~ B + ~ P = ~ A . Therefore ~ P = ~ A- ~ B . keywords: 005 (part 1 of 1) 10 points A B C D P R The vector ~ R shown in the sketch may be expressed in terms of ~ A , ~ B , ~ C , and ~ D , which are the edges of a parallelogram, as 1. ~ R = ~ A- ~ C . 2. ~ R = ~ B + ~ D . 3. ~ R = ~ D- ~ A . 4. ~ R = ~ C + ~ D . 5. ~ R = ~ A + ~ D . 6. ~ R = ~ C + ~ B . 7. ~ R = ~ A- ~ D . 8. ~ R = ~ A- ~ B . 9. ~ R = ~ B- ~ A . 10. ~ R = ~ B + ~ A . correct Explanation: The solution is found by the application of the parallelogram rule of addition; the tails of the two vectors ~ A and ~ B are joined together and the resultant vector is the diagonal of a parallelogram formed with ~ A and ~ B as two of its sides....
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## This note was uploaded on 04/15/2008 for the course PHY 2048 taught by Professor Guzman during the Spring '08 term at FAU.

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Homework 3 - Solutions - Maltese, James – Homework 3 –...

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