A cube with edge a is placed at the bottom of a cylindrical vessel with the cross-sectional area 3a2. The vessel also contains oil and water that behave, well, like oil and water. The densities of water, oil, and the cube are, respectively, d, 0.8d, and 2d. The depths of the water and oil layers are, respectively, 0.5a and a.
Find the minimum amount of work required to pull the cube completely out of the liquid.
Our November Challenge, Biting the dust, attracted quite a few solutions from teachers and students alike.
We are pleased to recognize the following contributors who solved the problem correctly:
Many thanks to all contributors and we hope to hear from many more of you in the future!
Note: as always, we would very much appreciate reader-contributed original Challenges.