First this is impact not a uniform load.
Safety glass breaks if hit by ceramic.
The impact of the shard against the glass creates a tiny structural failing which rapidly spreads the tension through the rest of the screen causing it to break.
When broken the pieces form razor sharp edges that can cause serious injury.
The glass may be able to resist 200kg of evenly distributed load but that is very different from a rock.
I can break a big piece of tempered glass with a little ceramic chip.
When safety glass shatters it is designed to stay in one place keeping all shards together and preventing sharp edges from harming people.
Why will a piece of ceramic break safety glass but a similar sized rock just bounces off.
Spark plugs are made of aluminum oxide ceramic which is exceptionally hard.
When safety glass is damaged in this way the damage propagates throughout the glass rapidly and the tension within the glass.
When regular glass shatters it breaks into several sharp pieces and spreads everywhere.
Although effective spark plug fragments will not work all the time.
Second the rock may have a hardness similar to the glass.
This concentrates the force of the hit to a small enough area on the glass that it can scratch and fracture it.
Breaking your car s windows in an emergency might be tougher than you think study says.
Normal float glass can be dangerous.
It is brittle so it breaks easily.