Question

blacksmith hammers a hot piece of iron while making a tool. how does the force due to hammering affect the piece of iron?

Answer 1

The property of iron that allows flattening of iron pieces when hammered is called malleability.  Due to this property, when a force is used like that on iron, the molecules spread out taking the force.  Then they move to sides and so the metallic piece spreads and flattens.

Answer 2

When a blacksmith hammers a hot piece of iron, he uses his muscular force, which changes the shape of the iron, so that it can be given a desired shape.