hw 6 - homework 06 HETTIGER, CHRISTOF Due: Jan 31 2008,...

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Unformatted text preview: homework 06 HETTIGER, CHRISTOF Due: Jan 31 2008, 4:00 am 1 Question 1, chap 3, sect 1. part 1 of 1 10 points A quarterback takes the ball from the line of scrimmage, runs backward for 11 yards, then runs sideways parallel to the line of scrim- mage for 18 yards. At this point, he throws a 23 yards forward pass straight downfield perpendicular to the line of scrimmage. What is the magnitude of the footballs resultant displacement? Correct answer: 21 . 6333 yards (tolerance 1 %). Explanation: Let the x direction be parallel to line of scrimmage. Given : y 1 = 11 yards , x = 18 yards , and y 2 = 23 yards . y tot = y 1 + y 2 = 11 yards + 23 yards = 12 yards x tot = x = 18 yards The displacements are perpendicular, so d = radicalBig ( x tot ) 2 + ( y tot ) 2 = radicalBig ( 18 yards) 2 + (12 yards) 2 = 21 . 6333 yards . Question 2, chap 3, sect 3. part 1 of 5 10 points A commuter airplane starts from an air- port located at the origin (see figure). First it flies to city A located a = 120 km away from the airport in a direction = 39 North of East. Next it flies b = 56 . 5 km = 38 West of North to city B. Finally it flies c = 178 km due West to city C. A B C O a c b r N N E W Consider E to be the positive x axis and N to be the positive y axis. Which of the following is equal to the x- component b x of the vector vector b ? 1. b x = b cos 2. b x = b tan 3. b x = b sin correct 4. b x = b cos 5. b x = b sin 6. b x = b tan Explanation: Let : b = 56 . 5 km = 38 Basic Concepts: The rule for adding two vectors vectorv = ( v x ,v y ) and vectoru = ( u x ,u y ) is vectorr = vectoru + vectorv = ( v x + u x ,v y + u y ) thus vector components add. Solution b | b x | | b y | Here is defined as the angle between vector b and a vertical line. Also, for < 90 ( as in this problem), vector b is in the 2 nd quadrant, i.e. its x component is negative and its y component positive. b x = b sin homework 06 HETTIGER, CHRISTOF Due: Jan 31 2008, 4:00 am 2 = (56 . 5 km) sin38 = 34 . 7849 km . Question 3, chap 3, sect 3. part 2 of 5 10 points Which of the following is equal to the y- component b y of the vector vector b ? 1. b y = b tan 2. b y = b tan 3. b y = b sin 4. b y = b cos correct 5. b y = b cos 6. b y = b sin Explanation: Let : b = 56 . 5 km = 38 b y = b cos = (56 . 5 km) cos(38 ) = 44 . 5226 km Question 4, chap 3, sect 3. part 3 of 5 10 points What is the x-component r x of vector vector r from the starting point, position O, to the city C in km?...
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hw 6 - homework 06 HETTIGER, CHRISTOF Due: Jan 31 2008,...

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