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Simple relative motion

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



Two ships, one moving 15 degree west of north with a speed 25 mi/h., the second moving 25 degree south of west with a speed 20 mi/h. relative to water pass each other. Find the velocity of the second ship relative to the first ship (magnitude and direction).

Homework Equations



V1 + r = V2
V2 - V1 = r

The Attempt at a Solution



I want to confirm on this.

My approach is using this relation.
V1 + r = V2
and so V2 - V1 = r, where r is the velocity we are looking for of our problem.

Then I will take components, x and y, and find sqrt(x^2+y^2) and direction tan-1 y/x
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
25,832
250
Hi jwxie! :smile:

(have a square-root: √ and try using the X2 and X2 tags just above the Reply box :wink:)
My approach is using this relation.
V1 + r = V2
and so V2 - V1 = r, where r is the velocity we are looking for of our problem.

Then I will take components, x and y, and find sqrt(x^2+y^2) and direction tan-1 y/x
Yes, that's exactly right! :smile:

(btw, I wouldn't use r, I'd stick to the same area of the alphabet, and use v12 or u or w :wink:)
 
  • #3
280
0
Hi, tiny, thank you for your confirmation. My friend had an exam and he doubted about my explanation. Thank you!

I will make sure I check all the synatx ^^
 

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