# Simple relative motion

jwxie

## 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).

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

Homework Helper
Hi jwxie! (have a square-root: √ and try using the X2 and X2 tags just above the Reply box )
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! (btw, I wouldn't use r, I'd stick to the same area of the alphabet, and use v12 or u or w )

jwxie
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 ^^