일반물리학 1 — Center of Mass and Linear Momentum: Problem 17

17 In Fig. 9-35a, a 4.5 kg dog stands on an 18 kg flatboat at distance $D = 6.1\text{ m}$ from the shore. It walks $2.4\text{ m}$ along the boat toward shore and then stops. Assuming no friction between the boat and the water, find how far the dog is then from the shore. (Hint: See Fig. 9-35b.)