Final answer:
Using vector addition principles, the magnitude of force F is 500 N when directed along the positive y-axis, and the direction θ is 0 degrees since the force is in the positive y-direction with no x-component.
Step-by-step explanation:
To determine the magnitude of force F and its direction θ, given that the resultant force is to be 500 N directed along the positive y-axis, you need to use vector addition principles. Since the problem mentions a force along the y-axis, it implies that there is no component in the x-direction. Therefore, the magnitude of force F is simply 500 N as there are no other forces along the y-axis mentioned. The direction θ would be 0 degrees since the force is entirely in the positive y-direction.
Magnitude of force F = 500 N; Direction θ = 0 degrees.