Answer:
it adds energy to the rock
Step-by-step explanation:
Because stress is a force, it adds energy to the rock. This stress/force is being applied to the rock. Whether the rock moves or not you are applying a force to the rock and it has potential energy. If the rock moves, you are adding energy to it and creating kinetic energy as the rock moves. Other forces such as gravity and friction can push against your force and prevent the rock from moving. Therefore, there are many forces at play in such a scenario.