Hey, I have two separate questions: 1) If one is moving in a car and throws a ball straight up, say out the sun roof, the ball will have zero velocity relative to an observer in the car. Conversely, it will have the velocity of the car to a stationary observer. How does one account for drag forces in this situation? Would the drag force be relativistic and if so, does the fact that the observer in the car sees the ball with zero velocity have significance? 2) I'm guessing there haven't been any experimental data on the subject, but is there any conjecture on the possible effects of relativistic velocities on human physiology? Just curious.