If there is a person walking along the road at the speed of 5km/h and a car traveling in the same direction as the person at 60km/h relative to the person. How to calculate their the distance between them? Also the velocity of light is 186 000 miles per second and what if both object X and Y can travel at 186 000 miles per second but object Y has an head start of 186 000 miles. How far apart would they both be in an hour? Or will there be no difference between them? Thanks also for your help.