Step 1: Recall the three main empirical laws of comminution (size reduction). These laws relate the energy input (E) to the change in particle size from an initial diameter (d$_1$) to a final diameter (d$_2$).
Rittinger's Law (1867): States that the energy required is proportional to the new surface area created. It is most applicable to fine grinding.
\[ E \propto \left( \frac{1}{d_2} - \frac{1}{d_1} \right) \]
Kick's Law (1885): States that the energy required is proportional to the logarithm of the reduction ratio. It is most applicable to coarse crushing of large particles.
\[ E \propto \log \left( \frac{d_1}{d_2} \right) \]
Bond's Law (1952): States that the energy required is proportional to the crack length produced, and it is the most widely used law for general crushing and grinding.
\[ E \propto \left( \frac{1}{\sqrt{d_2}} - \frac{1}{\sqrt{d_1}} \right) \]
The question specifically asks for the law involving the logarithm, which is Kick's Law.