How to get the XYZ Velocity from two Lat / Lon points?

Question

Lets say I have two XYZ ECEF (Earth Centered Earth Fixed) points, and I know the time it takes to get between them. How do I calculate the three dimensional xyz velocities? This is not a homework question, it's for a mapping project I'm working on and I'm not the greatest with GIS stuff.

Answer 1

As per your comment, you want Lat/Lng velocities. For this you need to know the time taken to travel. Then:

$latVelocity = ($start['lat']-$end['lat'])/$time;
$lngVelocity = ($start['lng']-$end['lng'])/$time;