Final answer:
A rock shattered by a hammer undergoes 1. brittle deformation, which is when a rock breaks instead of bending due to the stress exceeding its strength.
Step-by-step explanation:
A rock smashed into many pieces by a scientist using a hammer is undergoing 1. brittle deformation. When rocks are subjected to increased stress and strain, they may deform in various ways. Brittle deformation occurs when a rock breaks or fractures rather than bending, similar to glass shattering. This type of deformation is more common near the Earth's surface where rocks are cooler and less able to bend without breaking.
The definitions of the different types of stress are important to understand this concept. Compression stress occurs when rocks are pushed together, tension stress happens when rocks pull apart, and shear stress develops when rocks slide past each other horizontally. Brittle deformation happens when the stress exceeds the strength of the rock, leading to a breakage instead of a bend.