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Force Vectors

  • #1
Here is the link to the problem http://imgur.com/MGcfdr7 [Broken]


I'm not really sure how to approach this. I initially thought you would get the resultant vector by doing 125cos(38) and that gave me 98, which I then divided by the cos(45) to get the hypotenuse, or F2, which gave me 138.6. It says that this isn't the right answer so I'm not sure what to do.
 
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Answers and Replies

  • #2
80
1
Did you try to construct the parallelogram first?
 
  • #3
Did you try to construct the parallelogram first?
No, how would I go about solving for F2 with that?
 
  • #4
80
1
By using sine law. You have two angles and F1.
 
  • #5
By using sine law. You have two angles and F1.
Sorry, is there anyway you could set this up for me? I don't really understand what you're saying.
 
  • #6
80
1
Untitled.png

By using sine law you can easily get F2.
 
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  • #7
Untitled.png

By using sine law you can easily get F2.
Oh awesome, thank you! Just got it after digging through my memories of old geometry classes. Forgot about the angles flipping and all that jazz. Thanks for everything
 
  • #8
20,143
4,210
Here's another way which gives the same answer. Determine the components of the two forces in direction across the channel. They must be equal in magnitude and opposite in sign in order for the rear of the boat not to move in the cross channel direction.

Chet
 

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