(2) A laboratory experiment similar to the one conducted by Darcy is shown in the following figure. (a) What is the pressure head at point a in sand of the laboratory experiment shown below? (b) Assuming a porosity of 0.6 and k=1.7 x 102 cm/s, how long will it take a molecule of water to pass through from one end of the sand to the other? h = 0.8 m A = 0.2 m. L=0.8 m h = 0.2 m h= 0.6 m