The gas stream temperature is to be measured using a thermocouple with a junction that can be approximated as a $1\mathrm{.}0$ mm diameter sphere. The junction's thermal conductivity is k $=77$ W m$-1$K$-1,$ and the heat transfer coefficient between the junction and the gas is h $=150$ W m$-2$K$-1.$ Calculate the Biot number of the junction under these conditions. Provide the answer to five decimal places and enter the numerical value only $($e$.$g$.0\mathrm{.}12345).$THEN LABEL THIS AS PART $2,$ WITH WORKED ANSWERS For the problem above, use reasonable assumptions to determine how long it will take for the thermocouple junction to reach $0\mathrm{.}978$ of its initial temperature difference, such that $$left parenthesis increment T subscript i minus increment T right parenthesis divided by increment T subscript i$=0\mathrm{.}978.$ The junction material has a density of $8500$ kgm$-3$ and a specific heat of $320$ kJ kg$-1$ K$-1.$ Provide the answer to one decimal place and enter the numerical value only $($e$.$g$.20\mathrm{.}1$ but not $20\mathrm{.}1$ s$).$

Round your answer to $1$ decimal place.