How to draw vectors of an airplane & SE wind diagram

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Homework Help Overview

The discussion revolves around a problem involving vector addition related to an airplane's velocity and wind direction. The original poster describes difficulties in visualizing the vectors in a diagram, specifically how to represent the plane's intended northward velocity and the southeast wind vector accurately.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to create a diagram to visualize the vectors but finds that it does not lead to the expected resultant velocity. They question how the diagram should be set up and why it might be incorrect.
  • Some participants discuss the use of the Law of Cosines for calculating the resultant vector and raise questions about the directional interpretation of their results compared to the book's answer.
  • One participant expresses frustration with the method presented in the textbook and mentions seeking clarification from a teacher.

Discussion Status

The discussion is ongoing, with participants sharing their attempts at solving the problem and expressing confusion over the discrepancies between their calculations and the textbook's answers. There is a recognition of the need for clearer diagrammatic representation, and some guidance is offered regarding the interpretation of angles.

Contextual Notes

Participants note potential issues with the diagram setup and the interpretation of angles, as well as the challenge of finding a satisfactory method for visualizing vector addition. There is mention of a desire to clarify the textbook's approach and the original poster's inquiry about deleting multiple entries in the thread.

agentnan
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phys p85 #3.jpg
I can create/solve the math problem without any difficulties once I have diagram in place, but I am having trouble setting up the diagram so that I can visualize it. The questions is:

A novice pilot sets a plane's controls, thinking the plane will fly at 2.50 x10^2 km/h to the north. If the wind blows at 75 km/h toward the southeast, what is the plane's resultant velocity.

The diagram I have is starts with a vector going in a due north direction for 250km. At the top, I have the next vector going downward at a 45degree towards a SE direction. (see attached)


My resultant vector then would be from the tail of the first vector to the tail of the southeasterly vector.

While I can see what the answer SHOULD be...my diagram does not allow for the correct answer. Can someone please help me with what the diagram should look like and why?

Thanks so much!
 
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Again, http://upload.wikimedia.org/wikipedia/commons/thumb/e/ef/Vector_addition.png/467px-Vector_addition.png" .
 
Last edited by a moderator:
I am sure your response should help me, but I am still confused. This is the answer as I got it using the diagram I attached:
Using the Law of Cosines:
a^2 = (75)^2 + (250)^2 - w(75)(250)cos(45)
so my solution for a was 204.

For the directional, I got an answer of 15 degrees east of north. The book, however, says the answer is 75 degrees. I cannot figure out how to get their answer. Since my math appears to be correct, I am assuming that my diagram must be incorrect somehow.

Thanks...also can you let me know how to delete multiple entries? I tried the edit/delete button, but I do not see any delete options...only edit. Thanks for your patience!
 
agentnan said:
For the directional, I got an answer of 15 degrees east of north. The book, however, says the answer is 75 degrees.
Realize that 15 degrees east of north is equivalent to 75 degrees north of east.

(I deleted the multiple entries.)
 
Same Problem

I had the same problem. I was so desperate to find the answer so I typed the question into google and found this. The book has a stupid way of finding the answer (protractor way). I'm going to ask my teacher tomorrow about this one.
 

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