Hello everyone

I agree with Soroban's answer: I got a sign wrong in my working. My equation for the relative velocity was correct, though. The principle is:

*The velocity of A relative to B is the velocity of A minus the velocity of B.*

So, as I said:

not as you suggest: Originally Posted by

**steve989** ...

For that bit; wouldn't it be

? The signs switch as they are on different sides of the equation I assumed, but I may of miss-understood since I got a completely different answer anyway. Sorry about the layout too, I'm useless with this maths typing.

However, I then got a sign wrong when I equated the component of the displacement to zero. The equations should have been:

which, of course, are the same as Soroban's equations [1] and [2]. Originally Posted by

**steve989** ...I do have one question though for both you and grandad; why does the velocity vector of the destroyer end up with

as the scalar? I thought it was just

, I think I'm going to get a simple answer to that question though.

Thanks very much again for your answers.

Because the magnitude of is . So will have magnitude .

Grandad