A graduated cylinder contains 20.0 mL of water. After a rock is placed in the cylinder, the level rises as shown below. What is the volume of the rock?

The correct answer is 14 cm³.

Explanation:

Based on Archimedes Principle at rest when a body is completely or partially immersed within a fluid, it encounters a vertical thrust, which is equivalent to the weight of the fluid that the body displaces. In the mentioned case, the fluid is water. Thus, the rock being denser will result in the displacement of water, making the level of water to ascend in the cylinder.  

Thus, if V₁ or the initial volume is 20 ml or 20 cm³, and after insertion of the rock, the rise in the level of water becomes V₂ as 34 ml or 34 cm³. Then the volume of the rock will be,  

V = V₂ -V₁ = 34 - 20 = 14 cm³.