A Level Physics Practice Exam

A rubber band is considered elastic because it has the ability to return to its original length after a force is applied and subsequently removed. This characteristic is a key aspect of elastic materials, which are defined by their capacity to undergo deformation when a force is exerted and to recover their original shape once that force is no longer acting on them.

When a rubber band is stretched, the molecular chains within the rubber are forced apart. However, these chains are connected in a way that allows them to recoil to their initial configuration when the stretching force is removed. This recovery process is what defines elastic behavior, distinguishing it from materials that experience permanent deformation.

In contrast, the other options reflect properties that do not align with the definition of elasticity. If a rubber band stretched indefinitely, it would not have a limit to its elasticity and eventually break, which contradicts the recovery aspect. Stating that it can only be stretched once implies a lack of repeatability in elastic behavior, while becoming permanently deformed indicates that the material has lost its elastic properties. These distinctions emphasize the crucial aspect of resilience and reverting to original size that characterizes elastic materials.