Varieschi and Kamiya1 have derived expressions for the shear force and bending moment in a falling chimney from a detailed vector analysis of the forces that arise during this process. The authors predict that if the chimney breaks during its fall, it will most likely break at a position that is between one third and one half of the chimney height. They provide photographic evidence to show that real chimneys break at this predicted height. They discuss the “center of percussion” which is located at two-thirds of the length of the chimney from the base and define it as the point that “… is moving with the same acceleration as a particle under gravity, constrained to move along the same circular path.” Points higher up the chimney fall with greater acceleration and points below the percussion center fall with reduced acceleration, an effect known as the “free fall paradox.”...

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