$2.$ The viscosity of a fluid sample is measured in a cup and bob viscometer. The bob is $15cm$ long with a diameter of $9\mathrm{.}8cm,$ and the cup has a diameter of $10cm.$ The cup rotates, and the torque is measured on the bob. The following data were obtained:

$\backslash$table$[[(rpm),2,4,10,20,40],[T(dyncm),3\mathrm{.}6{10}^5,3\mathrm{.}8{10}^5,4\mathrm{.}4{10}^5,5\mathrm{.}4{10}^5,7\mathrm{.}4{10}^5$