Final answer:
A center punch is used to indent metal with the impact of a hammer, creating a guide mark for drilling.
Step-by-step explanation:
The tool that uses the impact of a hammer to indent metal before you drill a hole is called a center punch. When using a center punch, you place the sharp end against the metal surface where you want to drill. Then, you strike the top of the punch with a hammer. This creates a small indentation, or dimple, which helps to guide the drill bit when you start drilling, preventing it from wandering or slipping on the smooth metal surface.