Athin isothermal disk, having a diameter of 1.8 cm, is maintained at 40◦C and buried in a semi-infinite medium at a depth of 2 cm. The medium has a thermal conductivity of 0.8 W/m· ◦C and its surface...

Athin isothermal disk, having a diameter of 1.8 cm, is maintained at 40◦C and buried
in a semi-infinite medium at a depth of 2 cm. The medium has a thermal conductivity
of 0.8 W/m· ◦C and its surface is maintained at 15◦C. Calculate the heat lost by
the disk.