Final answer:
In equilibrium, each rope strand supports half the girl's weight, resulting in 250 N of tension in each rope, which answers the initial question.
Step-by-step explanation:
The question concerns the tension in ropes that are holding up a weight, which is a classic problem in Physics dealing with forces and Newton's laws. Since the girl weighs 500 N and is hanging motionlessly from the middle of a bar that is supported by two vertical strands of rope, the forces must be balanced. This is due to the fact that the system is in equilibrium, meaning the net force is zero. Therefore, each strand of rope must support half of the girl's weight to balance the forces, so the tension in each strand will be 500 N / 2 = 250 N.