An off-shore oil rig in the Atlantic Ocean has an empty spherical container resting on its horizontal deck. The container has an external diameter of 2.5 m, a mass of 200 kg, a smooth surface and it is bolted to a flat base with a mass of 20 kg and a diameter of 1.0 m. The container is normally strapped on the deck but, during some operation, the straps had not yet been secured, when a strong wing started blowing. The static friction coefficient between the base and the deck is 0.35. Determine the wind speed for which the container's base would start sliding on the deck, or tip over, whichever occurs first. Would this speed be higher or lower, if the surface of the container were covered with barnacles?

Contributed by Stavros Tavoularis, Department of Mechanical Engineering, University of Ottawa, Ottawa, Canada.