Final answer:
To mitigate the sway or ripple of a roadway, increasing the deck's stiffness through sturdier materials or structural supports can be effective, as a stiffer board vibrates faster with a shorter period. Conversely, adding mass to the system can also reduce movement but may not be practical due to weight considerations.
Step-by-step explanation:
To address the query, what helps stiffen the deck and reduces the tendency of the roadway to sway or ripple, we need to understand the concepts of stiffness and mass in the context of engineering and structural dynamics. The board's stiffness is directly related to how it will behave when forces are applied to it. A stiffer board has a tendency to vibrate more quickly, which means it has a shorter period of oscillation. That is, it will move up and down or back and forth more rapidly than a less stiff structure.
In contrast, the mass of the oscillating system also plays a critical role in how the system behaves. A heavier or more massive system tends to have a longer period, which means that it will take more time to complete one cycle of oscillation, such as the up and down movement observed with a person on a diving board. When this principle is applied to a roadway or bridge deck, the implication is that incorporating methods to increase the deck's stiffness, such as using sturdier materials or adding structural supports, can reduce movements like swaying or rippling.
Additionally, increasing the mass of the deck can also contribute to reducing such movements, though this is less desirable as it might require the structure to support additional weight, leading to the necessity of further reinforcements. Understanding these relationships is critical for designing and building structures that are both safe and practical.