Tempered Safety Glass is produced by heating and then cooling the glass; which statement describes its failure pattern?

• A. Shatters into large jagged shards
• B. Remains intact under most impacts
• C. Heats and cools glass to increase strength; breaks into tiny fragments
• D. Heats and cools the glass to increase tensile/yield strength

Answer: (D)

Tempered safety glass is produced by heating the glass and then rapidly cooling it. This tempering process puts the surface into compression, which raises the glass’s tensile/yield strength. That added strength explains why tempered glass behaves differently under impact: it can withstand higher forces, but when it does fail, it tends to break into many small pieces rather than large, sharp shards.

Among the statements, the one that describes heating and cooling to increase strength directly connects to how tempered glass is made and why its failure pattern occurs. The other statements describe outcomes or processes that don’t align with the tempering effect (such as remaining intact or shattering into large shards), so the strengthening-described statement best captures the essential concept.