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**1. Homework Statement**

A ship is moving at 0.45c with respect to earth, and a beacon is fired perpendicular to the ship at 0.65c with respect to the ship. Find the velocity of the beacon with respect to earth.

**2. Homework Equations**

**3. The Attempt at a Solution**

My main problem here is seeing which numbers go where in the equations. My book basically just shows them, then has an example of adding velocities in one dimension >_>.

From what I gather, u

_{x}and u

_{y}are the components of the velocity of the beacon with respect to earth. u'

_{x}and u'

_{y}are the components of the velocity in the ship's frame, making u'

_{x}= 0 and u'

_{y}= 0.65c

This however makes the v's in the denominator cancel out, and I get u

_{x}= v and u

_{y}= 0.65[tex]\sqrt{1/ (v^{2}/c^{2}})[/tex]

Plugging in my value of u

_{x}for v I get u

_{y}= 0.65[tex]\sqrt{1/ (u_{x}^{2}/c^{2}})[/tex] which doesn't lead me anywhere.

Its pretty clear that I'm doing something wrong, I just ned a nudge in the right direction. Here's my picture of the problem (not to scale =P)

http://www.geocities.com/zombierobopirate/relativity.png

Thanks in advance