We are using VR technology for people with spinal cord injury ( incomplete so they can walk with assistance) for a study. They will be walking on a treadmill wearing an oculus. We have a question regarding relative speed since we are updating the software view based on that if person A runs at 5 m/s , treadmill runs at 7 m/s , opposite direction of the person . If person B is watching, at what speed do they appear..aka whats the relative speed? what if treadmill and peron run in the same direction as person A . What speed does person B see him?