Automotive glass safety: A heat-treated (tempered) glass used in vehicles usually shatters into what form upon cracking, in order to reduce injury risk?

Introduction / Context:
Vehicle side and rear windows are commonly made from tempered safety glass to reduce injury risk in collisions or impacts. Understanding how tempered glass fails is important for safety engineering and repair decisions.

Given Data / Assumptions:

• The glass is properly tempered (heat-treated), not laminated.
• Upon critical stress or impact, the glass fails as designed.

Concept / Approach:
Tempered glass is created by heating followed by rapid quenching to build compressive surface stresses and tensile core stresses. This stored energy causes the pane, when fractured, to disintegrate into many small, relatively blunt particles instead of large sharp shards.

Step-by-Step Solution:

Verification / Alternative check:
Contrast with laminated windshield glass, which uses layers and PVB interlayer to hold shards together, typically preventing full shattering and ejection.

Why Other Options Are Wrong:

• Sharp edged fragments: typical of ordinary annealed glass, not automotive tempered glass.

Common Pitfalls:

• Confusing tempered and laminated glass roles in vehicles (windshields are typically laminated; side/rear often tempered).
• Assuming every automotive glass behaves the same upon impact.

Final Answer:
small particles