Answer to Question #283838 in Physics for riki

Question

a 4.5 kg dog stands on an 18 kg flatboat at distance D ! 6.1 m from the shore. It walks 2.4 m along the boat towardshore and then stops. Assuming no friction between the boat and the wa-ter, find how far the dog is then from the shore.

Answer 1

$$0=m_bv_b-m_dv_d,\\\space\\ v=\dfrac dt,\\\space\\ 0=m_b\dfrac{d_b}{t}-m_d\dfrac{d_d}{t},\\\space\\ 0=m_bd_b-m_dd_d.\\\space\\ d_b+d_d=2.4 \text{ m.}\\\space\\ d_d=1.92\text{ m},\\ d_d=0.48\text{ m}.\\\space\\ D_\text{dog}=6.1-1.92=4.2\text{ m}.$$