Halliday, Resnick & Walker — Force and Motion–I: Problem 42

In earlier days, horses pulled barges down canals in the manner shown in Fig. 5.25. Suppose the horse pulls on the rope with a force of 7900 N at an angle of $\theta = 18^\circ$ to the direction of motion of the barge, which is headed straight along the positive direction of an x axis. The mass of the barge is 9500 kg, and the magnitude of its acceleration is $0.12\text{ m/s}^2$. What are the (a) magnitude and (b) direction (relative to positive x) of the force on the barge from the water?