(a) A dam is usually much thicker at the bottom than at the top. Why?
(b) An engineer decides to use a successful dam design for a new lake of the same depth. If the new lake has ten times the surface area as the lake held by the original dam, what, if any, design changes are necessary for the new dam to hold back the increased amount of water? Explain your reasoning.
A cubical metal box has side L=10.## cm and mass m=150 g. How much mass must be placed inside the box if it is to float in water with its top at the surface?