This is a strange question from the physics Olympiade I wish to get some explanation for:
Using a certain type of wood, cubes are sawn with different edge lengths $R$. When they are on the ground, they are turned over one of the edges of the face touching the ground, so they rotate 90 degrees in the end. What is the relationship between the minimum energy $E$ required for this action and $R$?
- A. $E$ is proportional with $R$.
- B. $E$ is proportional with $R^2$.
- C. $E$ is proportional with $R^3$.
- D. $E$ is proportional with $R^4$.
The answers is D, but why?