Will a Spark Plug Shatter a Window?

A: Yes, a spark plug thrown at a car window will break it. So will a rock, a good-size ball bearing or a ball-peen hammer. The side widows are made of tempered glass that, while strong, can be broken with a strong blow. The glass will then shatter into cubes instead of shards so you are less likely to be seriously cut.

Why does a spark plug shatter windows?

A broken piece of spark plug has a Mohs hardness approaching that of diamond and most likely has sharp edges. this combination allows it to break the layers of the tempered windown. A rock has a lower hardness than aluminum oxide and most likely has a more spherical shape.

What will shatter a window?