The temperature of the gas stream is to be measured by a thermocouple whose junction can be approximated as a 1 mm diameter sphere. The properties of the junction are k = 35 W/m.°C, ρ = 8500 kg/m3, and Cρ = 320 J/kg. °C and the convection heat transfer coefficient between the junction and the gas is h = 210 W/m2. °C. Determine how long it will take in seconds for the thermocouple to read 99% of the initial temperature difference.