Answer
$\Delta$$E_{th}$=+30 Joules
Work Step by Step
The total Work done on the system is +200J. +60 Joules of work is preformed on the block, and +130 Joules of kinetic energy is introduced. This is a total of 190 Joules. Because the cylinder is pulled down, potential gravitational energy decrease (-20 Joules). The total is now 170 Joules. The only factor left un-calculated is thermal energy, so it must fill in the gap. 200-170= +30 Joules.
