Chasing Across the Field

A man and his dog are positioned at opposite ends of a 100-foot-long football field. They begin running towards each other simultaneously. Assume the man's speed is x ft/s, while the dog runs at twice the man's speed. Each time the dog reaches the man, it turns around and runs back to its starting point, then returns to the man, repeating this cycle. Calculate the total distance the dog travels by the time the man reaches the opposite end of the field.