a 175 lb man sits in the middle of a 54 lb, 12 ft long boat. the boat’s prow touches the pier, but the boat isn’t tied to it. the man stands up and walks towards the pier. assume there is negligible resistance between the boat and water, and that the boat’s center of mass is in the middle of the boat. by the time he reaches the boat’s prow, what is the distance between the prow and the pier? answer in units of ft