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Magnitude and direction

  • Thread starter lalahelp
  • Start date
  • #1
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Homework Statement


Orv walks 312 m due east. He then continues walking along a straight line, but in a different direction, and stops 220 m northeast of his starting point. How far did he walk during the second portion of the trip and in what direction?
What is the magnitude?
What is the direction ___________ ° counterclockwise from the +x-axis



Homework Equations


C=squareroot of 312^2+220^2
What equation to use to find direction??

The Attempt at a Solution


C= Magnitude= 381.76 m why is my magnitude wrong?
 

Answers and Replies

  • #2
9
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A good idea here is to read the problem carefully, and/or make a simple diagram.
You're correct in using the Pythagorean theorem for this problem, but you're using it incorrectly. Remember that the form is a^2 + b^2 = c^2, where c is the hypotenuse.

In the problem statement, you're given a = 312 meters (The distance walked east -- one of the legs of the triangle), and c = 220 meters (The distance in a straight line from the starting point -- the hypotenuse).

This means that what you need to find here is b, not c.
 
  • #3
10
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As with regards to your direction issues, once you have your three sides figured out, use your trig laws (soh cah toa).

If you've never heard of them, it goes:
"soh" - sin = opposite / hypotenuse
"cah" - cosine = adjacent / hypotenuse
"toa" - tangent = opposite / adjacent

And you should get the right answer.
Cheers

EDIT: or your sin/cosine laws. I didn't work through the problem myself, I just assumed based on the level it was a right angle triangle.
 
  • #4
9
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EDIT: or your sin/cosine laws. I didn't work through the problem myself, I just assumed based on the level it was a right angle triangle.
Same. Now that I look at it (through my sleepy eyes), the 'hypotenuse' is shorter than one of the legs, and by a good bit, too...
 
  • #5
75
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I cant take the square root of a negative number for the magnitude... Is there another way to solve this...
 
  • #6
156
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Homework Statement


Orv walks 312 m due east. He then continues walking along a straight line, but in a different direction, and stops 220 m northeast of his starting point. How far did he walk during the second portion of the trip and in what direction?
What is the magnitude?
What is the direction ___________ ° counterclockwise from the +x-axis
Did you ever draw it?
 

Attachments

  • #7
@:AC130NAV: The problem states that the final position was 220 m from the starting point in an north easterly direction, so your drawing is not correct.
 
Last edited:

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