A paddle wheel frictionally adds thermal energy to an ideal monatomic gas in a sealed, insulated container. The paddle wheel is driven with a cord connected to a falling object as shown in the drawing. In this experiment, a 5.0-kg object falls during a total distance of 3.0 m and the temperature of the gas is found to increase by 6 C°. Suppose that all of the mechanical energy lost by the falling object goes into the gas. How many moles of gas should be present in this container?