Final answer:
A free-hand drawing that describes the shape and size of an object is called a sketch, which is used early in the design process to conceptualize ideas.
Step-by-step explanation:
A free-hand drawing used to describe the shape and size of an object is known as a sketch. In the early stages of the design process, sketches serve as a means for engineers and designers to understand and explore design concepts, including their strengths and weaknesses. A sketch allows for quick visualization and is an integral part of developing initial design ideas. Subsequently, these ideas can evolve into more detailed designs and eventually be represented through scale drawings, models, or prototypes, each serving different functions in the design process. Scale drawings are precise and use specific units of measure to represent larger units, while models can represent the design in three-dimensional space, usually to a smaller scale. Prototypes, on the other hand, are either physical or computer-generated preliminary versions of the final design, used to evaluate the design and find any potential flaws before final production.