Help with adding vectors with component method (sin/cos/tan)

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SUMMARY

The discussion focuses on resolving vector components using trigonometric functions (sine, cosine, and tangent) for two specific scenarios: a ship's displacement and an army recruit's movement. The ship travels 30 miles north and then 50 miles at a 60-degree angle east of north, while the recruit follows a complex path involving multiple bearings. Participants highlight confusion regarding the correct application of angles, particularly the distinction between "north of west" and "west of north," which affects the orientation of the x and y components in their calculations.

PREREQUISITES
  • Understanding of vector components and their representation in a Cartesian coordinate system.
  • Proficiency in trigonometric functions: sine, cosine, and tangent.
  • Familiarity with angle measurement and conversion between bearings and standard angles.
  • Ability to interpret and draw vector diagrams accurately.
NEXT STEPS
  • Study the concept of vector addition and how to resolve vectors into components.
  • Learn about angle measurement conventions, particularly bearings and their implications on vector direction.
  • Practice solving problems involving multiple vector displacements using trigonometric functions.
  • Explore graphical methods for vector addition, including the use of vector diagrams.
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Students in physics or mathematics, particularly those studying vector analysis, trigonometry, or preparing for exams involving vector problems.

amd123
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Homework Statement


A ship leaving its port sails due north for 30 miles and then 50 miles in a direction of 60 degrees east of north. At the end of this displacement, where is the ship relative to its port?

An army recruit on a training exercise is instructed to walk on a bearing of 6.3 degrees north of west for 5 miles, then on a bearing of 41 degrees north of east for 4 miles, and finally on a bearing of 15 degrees west of north for a direction of 3 miles. Determine the distance and direct the recruit must walk to return to his starting position?



Homework Equations


What is the difference between let's say North of West and West of North and how does this make my drawing of the triangles different? Because for these two problems my teacher said I have my x and y values reversed because of how I drew the triangles because of the description of the direction.

I know I'm doing the sin/cos/tan functions correctly but I get my values in the opposite places X for Y and vice versa because of the north of west and west of north concept.

Can someone please explain it to me?



The Attempt at a Solution


http://img231.imageshack.us/my.php?image=77107532lx7.jpg
http://img231.imageshack.us/my.php?image=74381618jo2.jpg
according to my teacher my answers are wrong... what am i doing wrong?
 
Last edited:
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amd123 said:

Homework Statement


A ship leaving its port sails due north for 30 miles and then 50 miles in a direction of 60 degrees east of north. At the end of this displacement, where is the ship relative to its port?

An army recruit on a training exercise is instructed to walk on a bearing of 6.3 degrees north of west for 5 miles, then on a bearing of 41 degrees north of east for 4 miles, and finally on a bearing of 15 degrees west of north for a direction of 3 miles. Determine the distance and direct the recruit must walk to return to his starting position?



Homework Equations


What is the difference between let's say North of West and West of North and how does this make my drawing of the triangles different? Because for these two problems my teacher said I have my x and y values reversed because of how I drew the triangles because of the description of the direction.

I know I'm doing the sin/cos/tan functions correctly but I get my values in the opposite places X for Y and vice versa because of the north of west and west of north concept.

Can someone please explain it to me?



The Attempt at a Solution


http://img231.imageshack.us/my.php?image=77107532lx7.jpg
http://img231.imageshack.us/my.php?image=74381618jo2.jpg
according to my teacher my answers are wrong... what am i doing wrong?

Let's say that the x-axis runs in the E-W direction and the y-axis in the N-S direction. Then, 30 miles north of west would be 30 units above the -x axis, with the angle between the line connecting the origin and the point and the -x axis being your desired angle.
 
there i posted my work
 

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