What is the main idea of the passage?

Repeated bending concentrates damage and grows tiny cracks until metal finally breaks. (The passage traces repeated force from a narrow bend through blocked movement and growing microscopic cracks to fatigue failure.)

Why can a scratch make repeated-force failure more likely?

It can concentrate stress where a microscopic crack begins. (The passage says cracks can begin where scratches concentrate stress, giving repeated bending a place to extend the damage.)

What does “concentrated” mean in the first paragraph?

Focused in a small area (The force is described as acting in a narrow region rather than across the whole object, so it is focused there.)

Which design choices can slow the failure process?

Rounded corners, smoother surfaces, and suitable loads (The final paragraph directly names rounded corners, smoother surfaces, and loads kept within a suitable range.)

Why Metal Breaks at the Bend: Level 3 Reading Comprehension Questions

Bend a metal paper clip once, and it usually keeps its new shape. Bend the same spot back and forth many times, and the clip eventually breaks. The force is not spread across the whole object. It is concentrated in a narrow region where the metal repeatedly changes direction.

Metal is made of crystals whose atoms sit in ordered patterns. Under force, tiny defects in those patterns allow layers to shift. Repeated bending rearranges and blocks that movement, making the worked area harder to deform. At the same time, microscopic cracks can begin near the surface, especially where scratches or sharp corners concentrate stress.

Each new bend opens those cracks a little farther. The unbroken section then carries more of the load, so the damage speeds up until the remaining metal separates. Engineers call this kind of failure fatigue. A part can therefore break under repeated forces that would not snap it in one attempt. Rounded corners, smoother surfaces, and loads kept within a suitable range can slow the process. The broken clip offers a small example of why machines must be designed for repetition, not merely for one strong push.

Comprehension questions