The rock will break because it can be stretched no farther.
An object stretched beyond its elastic limit may be deformed (adopt a new permanent resting shape) or break.
A stretched rubber band.
Elastic potiential energy is the energy stored when an object is squeed or stretched.
elastic energy is produced when something is stretched and the tension in the object is called elastic potential energy.
Elastic potential energy depends on the distance the object is compressed or stretched.
If a force is too great, the elastic limit will be exceeded. After the elastic limit is an area called the plastic region. The object may be stretched further in this area, however it will not returned to its original shape and will be permanently distorted. Eventually, the object will reach its breaking point. If the force applied is within the elastic limit, the object will return to its original shape.
Elastic Potential energy
Elastic potential energy because it is the potential energy of an object that is stretched or compressed.
Elastic energy, for example, a stretched spring.
Elastic Deformation
There are three main types of potential energy: elastic potential energy, gravitational potential energy, and chemical potential energy. Elastic potential energy is stored in objects that can either be stretched or compressed. The more the object is stretched or compressed, the more elastic potential energy it'll have.
Gravitational potential energy, is the energy an object possesses by reason of its position in a gravitational field. While elastic potential energy, is the energy stored by a material or object as a result of deformation e.g. the energy stored in a bow when it is stretched.
Elastic deformation means that while the force is applied to a body some deformation ( bending , streching , etc) will take place but as soon as the force is removed the body will return to its original shape with no defects.