A dog, with a mass of 8.0 kg, is standing on a flatboat so that he is 26.8 m from the shore. He walks 8.6 m on the boat toward the shore and then stops. The boat has a mass of 36.0 kg. Assuming there is no friction between the boat and the water, how far is the dog from the shore now?

Answer 1

Use the fact that the center of mass of boat + dog stays in the same place.