When a pole as shown in Fig. 2 is straight stood to the bottom of the vessel of a rectangular prism as shown in Fig. 1, find the depth of the water ?
Answer
16 cm
Solution
The base area of the vessel is 8 × 8 = 64 cm2, and base area will be changed to 64 - 2 × 2 = 60 cm2 when the pole is put in.
Since the volume of water does not change, the ratio of base area to the depth of the water turns into an inverse ratio.
Since the ratio of base area is 64 : 60 = 16 : 15 and the ratio of the depth of the water is set to 15 : 16, it is 16 cm.
<Another solution>
The volume of water is 8 × 8 × 15 = 960 cm3, and the base area putting in a stick is changed to 64 - 2 × 2 = 60 cm2, then the depth of the water is 960/60 = 16 cm.
