Boat B is towed by boat A through cable C. Both boats move forward in a constant speed. It is known that the cable is inextensible and its bending stiffness is negligible. The total length of the cable is 40 m. Its mass per unit length is 5 kg/m. The drag force on boat B is F_D= 4000N. Find the distance L between the two boats and the sag d.
