Mass wasting. Water filling a thin crack in a rock wall and then freezing can put large forces on the rock, making the cracks bigger (Fig. P14.69). 

(a) Calculate the force exerted by a 10-m² area of a thin (0.50 mm) sheet of water freezing between two slabs of rock. 

(b) Take the sheet of water to be oriented in a horizontal plane (unlike the case in Fig. P14.69) and assume a large slab of rock sits on top of the ice. By how much is the rock on top of the water displaced vertically? 

(c) If the column of rock is 15 m tall and has a density of 5.2 g/cm³, how much work is done by the expansion of the ice on this rock mass?

Figure P14.69