Idea: Putting iron blocks into water under different conditions means that the volume of iron blocks immersed in water is equal to the volume of water that the water surface rises relative to the initial state.

Solution: (1) When the iron block is placed horizontally, the height of the iron block becomes 8cm and the height of the water is 8cm, so the iron block is completely immersed in the water. Let the water level rise by x centimeters.

π× 10? ×(x+8)- 15×8×8 = π× 10？ × 8 (total volume-iron volume = initial water volume)

X=3. 1。

(2) When the iron block is placed vertically, the water level is only 8+3.1=11.1cm because the iron block is completely immersed in the water in the first case. So in the second case, the iron block is not completely immersed in the water.

Suppose the water level rises by x cm.

π× 10? ×(x+8)- (x+8)×8×8 = π× 10？ × 8 (total volume-iron volume = initial water volume)

X=2.0

This question needs to be considered, whether the iron blocks are all immersed in water.

In fact, there is still a problem to consider: can the iron be put in smoothly? Since it is a primary school topic, this problem can be ignored.

There may be a small error after the decimal point. I hope it will be helpful to this classmate. If you have any questions, you can ask. I wish you progress in your study!