<image>As shown in the figure, the radius of the base of a cylindrical container is 6 cm. When a piece of iron is placed into the container and completely submerged in water, the water level rises by 3 cm. What is the volume of this piece of iron? If it is placed into another cylindrical container with a base radius of 3 cm and is completely submerged in water, by how many centimeters will the water level rise?