Pressure - Need to know force - Explanation

Pressure - Need to know force Pressure is defined as force per unit area. The area over which a force is applied affects how much **pressure** it exerts on a body. A force that is exerted over a small area results it a large pressure, while the same force spread over a larger area would result in a small pressure. This is because pressure (\\(P\\)) is force (\\(F\\)) per unit area (\\(A\\)). $$ P = \frac{F}{A} $$ This is why stepping on a nail is very painful and will cause the nail to stab into your foot, but it is possible for performers to lie on a bed of nails relatively painlessly. In the first example your weight is being applied to a very small area (large pressure), whereas in the second you weight is spread out over a much wider area (small pressure). Since pressure is defined as force per unit area, and the student needs to know both the magnitude of the force (i.e. the weight of the box) and also the area over which it is applied (i.e. the surface area of the base of the box).

3 years ago