Final answer:
The gravitational force is primarily responsible for the tension in wires stretched between two poles because it causes an upward tension to counteract the downward gravitational pull on any weight added to the wire.
Step-by-step explanation:
The force primarily responsible for the tension in wires stretched between two poles is the gravitational force. This is because, when an object such as a wire is hung between two points and a weight, like a tightrope walker, is applied, the wire bends and creates an upward tension force to counteract the downward pull of gravity on the weight. As the wire supports this weight, the tension throughout the wire adjusts, maintaining an equilibrium with the force of gravity.
In the context of a tightrope walker, the system includes the tightrope walker and the wire, with the wire experiencing forces of tension on either side (T₁ and TR) and the weight of the walker acting downwards due to gravity. These tensions have upward components that balance the gravitational force. The magnitudes of T₁ and TR are equal, ensuring no horizontal acceleration occurs, which causes these horizontal components to cancel each other out.