text: why is it when im on a train and i jump the train doesnt keep going leaving me in the air???????? know what i mean? you're going forward with the train; you're not in a stationary position.  that's why if you've ever tried to jump out of a moving vehicle and land on your feet you get wrecked-- just because you're sitting still doesn't mean that you're not moving.  but if you jumped off the back of a moving train, would you be jumping forward or backward?