Answer :
Final answer:
It is true that hammer drills and rotary hammers combine rotational motion with a percussive hammer action, effectively drilling into hard materials by breaking them up more efficiently than by rotation alone.
Explanation:
The statement that both a hammer drill and rotary hammers not only rotate but also add percussion action is true. These tools are designed to drill into hard materials such as concrete and masonry. They combine a rotational motion with a hammering action that moves the drill bit in and out along the axis of the bit as it spins, which helps to break up the material more effectively than rotation alone. This hammering action is what differentiates them from regular drills, which only rotate without any percussive impact.
