1. Force (F): Force is directly proportional to pressure provided the area is kept constant. That is, if force is increased pressure will also increase.
2. Area (A): Area is inversely proportional to pressure provided the force is kept constant. That is, if area is increasing, pressure will reduce.

MAXIMUM AND MINIMUM PRESSURE

                                                                                          l= length

                                                                       h                w= width

                                                                                           h= height

                                                                    w

                    l

Maximum Pressure= weightheight*width

Minimum Pressure= weightlength*width

Example: A box of dimension 8m by 6m by 2m has a mass of 480kg. Take g=10m/s², calculate the:

1. Weight of the box.
2. Maximum pressure exerted by the box.
3. Minimum pressure exerted by the box.

Solution

1. Weight= mass*gravity

But mass = 480 kg and gravity = 10m/s²

Therefore, gravity = 480kg*10m/s² = 4800N

                                                2m                Pmax= Weight / (h*w)   

                                                  6m              but h=2m, w=6m and weight=4800N

                           8m                                     Pmax = 4800N / (6m*2m)= 4800/12

                                                                       Pmax = 400N/m²

3. Pmin = weight / (l*w) = 4800N/ (8m*6m)

                    Pmin = 4800N / 48m

                    Pmin = 100N/m²