Ive always puzzled about this one, if your on a train and its moving fairly fast and your standing in the isle if you jump in the air, when you land will you land on the same spot you jumped from, or would the train have moved while your in the air and you land somewhere different.
Before you jump, while standing perfectly still on the train there isn't any force that you feel pushing you backwards.
Such a force doesn't suddenly appear when you jump
Bur if you do it on the top of an open topped bus the outside air speed is travelling at a different rate to the bus so you would be blown backwards for sure, I think!!