Final answer:
The elasticity of the resistance band determines the ease of its stretchiness or flexibility, governed by the elastic modulus and elastic limit. Doubling up bands changes their combined elasticity, with parallel bands stretching less and series bands stretching more cumulatively under the same load. Compressive stress is also applicable to rubber bands, though tensile stress is more characteristic of their use.
Step-by-step explanation:
The elasticity (stretchiness) of the resistance band determines the ease of stretchiness or flexibility of the band. This is a concept related to the physical properties of materials that describes how they deform under various loads. The elastic modulus and elastic limit are crucial in understanding a material's elasticity. A high elastic modulus indicates a material that requires a significant force to stretch it, while a low elastic modulus describes a material that stretches easily.
When doubling up resistance bands, the proportionality constant k plays a role in their combined elasticity. If two bands are placed in parallel, they will stretch less than a single band under the same load due to the distribution of the force across both bands. In series, however, the total stretch will be the sum of the stretch of each band.
Compressive stress can be applied to a rubber band, although it is not as common as tensile stress, which occurs when pulling on a rubber band.