This lecture is an introduction to transient or unsteady heat conduction with emphasis on the lumped system approach. The equation that models a lumped system was derived and two examples were done. The one example was for a small sphere made from stainless steel and the other example was on the cooling of a bear can. The Biot number was also introduced as a criterion on the applicability of a lumped system approach. Lecture is based on the textbook of Cengel and Ghajar (4th ed) and was presented as part of a heat transfer class to the fourth year students of the Department of Mechanical and Aeronautical Engineering by Prof Josua Meyer, Head of the Department of Mechanical and Aeronautical Engineering of the University of Pretoria, South Africa. Lecture was presented on 5 February 2014.
