if there is a crack in a rock, then water can get into the crack & when water freezes , that water expands ->  if water freezes in the crack of the rock, then water will expand in the crack  if water freezes in the crack of the rock, then water will expand in the crack & if water expands in a crack in a rock, then the rock will break apart -> if water freezes in the crack of the rock, then the rock will break apart by water expanding when it freezes