# General Case of Relative Velocities

• Quarlep
In summary, the conversation discusses the general case of velocity addition in relativity, with a focus on the formula and a typo that may be present. The conversation also clarifies the meaning of the vectors involved and their representation in the formula.

#### Quarlep

I was looking relative velocities and I saw General case in Relativity part.That part means every direction isn't it.
http://en.wikipedia.org/wiki/Relative_velocity
and in there B is the observer or A is the observer
Thanks

Quarlep said:
I was looking relative velocities and I saw General case in Relativity part.That part means every direction isn't it.
http://en.wikipedia.org/wiki/Relative_velocity
and in there B is the observer or A is the observer
Thanks

With respect to the general case of velocity addition in the wiki, there appears to be a (typo) in the formula.

I see two vectors (velocity A and velocity B) side by side in the denominator of the fraction. Most likely this is a dot product but there is no dot between them.

Yes? No?

Quarlep said:
in there B is the observer or A is the observer

##\vec{v}_{BA}## is the velocity of B in the rest frame of A, which needs to be calculated; ##\vec{v}_A## and ##\vec{v}_B## are the velocities of A and B in some other frame, which are presumed to be known at the start of the calculation.

MikeLizzi said:
Most likely this is a dot product

Yes, there should be a dot between them.