Final answer:
In Physics, to find the velocity of the wind when given the velocity of a boat relative to shore and the water current, the equation to use is w = v - c, representing the wind's velocity as the difference between the boat's velocity relative to shore and the current's velocity.
Step-by-step explanation:
The question addresses the concept of relative velocity, which is a key principle in Physics that applies to scenarios like navigation of sailboats. In the case presented, a sailboat is in a water current moving due north at a speed of 5 m/s and also experiences a wind that results in the sailboat's actual speed relative to shore being 5√3 m/s in a direction of 60° north of east. The equation needed to find the wind's velocity in terms of the current (c) and the velocity of the sailboat relative to the shore (v) is w = v - c. This is because the wind's velocity vector (w) would be the difference between the sailboat's velocity relative to shore and the current's velocity; visually, this can be represented in a vector diagram and solved analytically through vector components.