# oldhw3_s - oldhomewk 03 – YOO HEE – Due 4:00 am 1...

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Unformatted text preview: oldhomewk 03 – YOO, HEE – Due: Jan 22 2008, 4:00 am 1 Question 1, chap 2, sect 1. part 1 of 2 10 points A physics book is moved once around the perimeter of a table of dimensions 1 m by 3 m. If the book ends up at its initial position, what is the magnitude of its displacement? 1. 3 m 2. 7 m 3. 8 m 4. 2 m 5. 0 m correct 6. 5 m 7. None of these 8. 1 m 9. 4 m 10. 6 m Explanation: Since its final position is the same as its initial position, the displacement is . Question 2, chap 2, sect 1. part 2 of 2 10 points What is the distance traveled? 1. 1 m 2. 4 m 3. 5 m 4. None of these 5. 2 m 6. 8 m correct 7. 3 m 8. 6 m 9. 0 m 10. 7 m Explanation: The distance traveled is the perimeter of the table: d = 2 ℓ + 2 w = 2 (1 m) + 2 (3 m) = 8 m . Question 3, chap 2, sect 3. part 1 of 1 10 points The slope at any point of a distance-time graph represents 1. instantaneous velocity. correct 2. average force. 3. displacement. 4. average acceleration. 5. instantaneous acceleration. Explanation: The slope of a graph represents its deriva- tive, and the time derivative of distance is instantaneous velocity. Question 4, chap 2, sect 1. part 1 of 2 10 points A bus travels 310 km south along a straight path with an average velocity of 93 km/h to the south. The bus stops for 26 min, then it travels 230 km south with an average velocity of 67 km/h to the south. a) How long does the total trip last? Correct answer: 7 . 1995 h (tolerance ± 1 %). Explanation: oldhomewk 03 – YOO, HEE – Due: Jan 22 2008, 4:00 am 2 Basic Concepts: Δ x = v avg Δ t 1 h = 60 min Given: Δ x 1 = 310 km south v avg, 1 = 93 km / h south Δ t 2 = 26 min v avg, 2 = 0 km / h Δ x 3 = 230 km south v avg, 3 = 67 km / h south Solution: t total = Δ t 1 + Δ t 2 + Δ t 3 = Δ x 1 v avg, 1 + Δ t 2 + Δ x 3 v avg, 3 = 310 km 93 km / h + (26 min) · 1 h 60 min + 230 km 67 km / h = 7 . 1995 h Dimensional analysis for Δ t : km ÷ km h = km · h km = h Question 5, chap 2, sect 1....
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oldhw3_s - oldhomewk 03 – YOO HEE – Due 4:00 am 1...

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