A class of 180 students sits in a lecture theatre for one hour, each student metabolising at 100 W. The lecture theatre is a cubic room ten metres long on each side and ten metres high. The specific heat of air at constant volume is 1 kJ kg-1 K-1 . The density of air is about 1.2 kg m-3 . The initial temperature was 20?C. The ventilation is poor, the air conditioning is broken and the walls are well insulated. What is the room temperature at the end of the lecture? Compare this to the sun, which produces 3.86 × 1026W.