What qualifies a hammer as a sledgehammer?

A hammer qualifies as a sledgehammer primarily due to its design and intended use, specifically its length and weight. A sledgehammer is characterized by its heavy head and a long handle, which combine to require both hands for effective use. This design allows for greater force to be applied when striking, making it suitable for tasks such as driving stakes, breaking up concrete, or demolishing structures.

The weight and length enable the user to generate momentum with a swinging motion, effectively transferring that energy into the object being struck. In contrast, a hammer that is lightweight or designed for one-handed use lacks the properties typical of a sledgehammer. Similarly, the material or surface being struck does not define a sledgehammer, as it can be used on various surfaces, including metal and masonry, rather than being limited to just wood.