Who lies on a bed of nails? Magicians, some who practice extreme forms of meditation and...physics students!
How can they do this without being punctured by the nails?
A single nail has a sharp point – any force applied to this point is being concentrated onto a small area. Therefore the force per unit area (i.e., pressure) is large for a single nail. If the same force is spread out over several nail points, the force per unit area decreases (i.e., pressure decreases). The pressure on each nail point will decrease when more nails are added to the "bed." |
