Final answer:
A wire supporting a large picture is less likely to snap if it sags considerably, as this allows for more even distribution of tension and reduces stress at any single point. A tightly strung wire concentrates stress, making it more prone to snapping.
Step-by-step explanation:
The question involves determining whether a wire supporting a large picture is more likely to snap if it is strung tightly or if it sags considerably. When the wire sags, it allows for a more even distribution of tension across the length of the wire. In contrast, a wire that is strung too tightly concentrates stress at specific points, particularly where it is connected to the nails. This concentration of stress can increase the likelihood of the wire snapping due to a weaker distribution of the supporting forces. Additionally, a wire that sags considerably forms a natural curve (catenary) that enables it to support the picture with the forces more evenly distributed, reducing the risk of breaking.
In physics, this relates to how the force of tension is applied and distributed along the wire. The sag allows for the tension to be distributed more optimally, which reduces the force on any single point along the wire, decreasing the chance of failure. Wire tension and the principles of stress and strain are important factors in ensuring that the picture remains supported without causing the wire to snap.