Question

Give reasons why:

a single nail pricking the body is painful when compared to lying on a bed of nails.

Answer 1

In a nail bed, the weight is evenly distributed among numerous nails, so that the pressure exerted by each nail is not enough to puncture a person’s skin. If it's only a single nail, the entire force created by the weight of the body would be distributed over a very small area presented by the tip of one nail. In this case, the force per unit area will be great and can puncture the skin.