Extracted text: Further problems 293 A vertical masonry chimney has a internal diameter d, and an external diameter d,. The base of the chimney is given a horizontal acceleration a m/s’, and the whole chimney moves horizontally with this acceleration. Show that at a section at depth h below the top of the chimney, the resultant normal force acts at a distance ah/2g from the centre of the section. If the chimney behaves as an elastic solid, show that at a depth g(d,² + d,)/4ad, below the top, tensile stress will be developed in the material. (Cambridge) 12.5