Final answer:
To calculate the drag force of the water on the barge, one must determine the net force using the mass and acceleration of the barge, and then subtract the combined forces applied by the tugboats from this net force.
Step-by-step explanation:
The question asks about calculating the drag force of the water on the barge, which is a classic physics problem of Newton's second law applied in a real-world context. Given that the mass of the barge is 5.0×106 kg and the acceleration is 7.5×10⁻² m/s², we can find the net force acting on the barge using the equation F = ma, where F is the net force, m is the mass, and a is the acceleration. The net force is the vector sum of the applied forces from the tugboats and the drag force of the water. Since we know the applied forces and the acceleration, we can solve for the drag force by rearranging the equation to find Fᵤᵗᵒᵦ - Fᵡᵐᵐ, where Fᵤᵗᵒᵦ is the net force (obtained from mass and acceleration) and Fᵡᵐᵐ is the sum of the forces exerted by the tugboats.