Beer bottles turn up in physical disputes, and forensic pathologists have to say afterwards what happened. A bottle that breaks produces ; one that stays intact produces blunt injuries. Nobody had measured which of the two a full bottle delivers.
The empty one. In a test of standard half-liter bottles, full bottles broke at 30 J of and empty bottles at 40 J, so it takes a third more energy to break an empty bottle. Both of those thresholds surpass the minimum of the human neurocranium, which is what makes the comparison worth running at all.
Beer bottles are often used in physical disputes, which puts a mundane object into forensic casework. If the bottles break, they may give rise to sharp trauma; if they remain intact, they may cause blunt injuries.
Two questions follow from that, and the authors ask both. Are full or empty standard half-liter beer bottles sturdier, and does the necessary breaking energy surpass the minimum fracture-threshold of the human skull?
The method is deliberately simple. The authors tested the fracture properties of such bottles in a drop-tower, which delivers a measured impact energy rather than the uncontrolled one of a real altercation.
Full bottles broke at 30 J of impact energy, a third less than the 40 J the empty ones needed. Both of those breaking energies surpass the minimum fracture-threshold of the human neurocranium, which means beer bottles may fracture a human skull and serve as dangerous instruments in a dispute.
wat. The empty bottle took 40 joules; a skull needs less.
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In a forensic reconstruction, whether the bottle broke tells you which injuries to expect, and both answers are serious.
How do we know?
Bolliger and colleagues tested the fracture properties of standard half-liter beer bottles in a drop-tower, comparing full against empty, and set the results against the published threshold for skull fracture.
What is still unknown
One bottle type in a drop-tower, which is a cleaner geometry than any real impact.
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