A 4-mm·diameter spherical ball at 50°C is covered by a 1-mm-thick plastic insulation (k =...

A 4-mm·diameter spherical ball at 50°C is covered by a 1-mm-thick plastic insulation (k = 0.13 W/m·K). The ball is exposed to a medium at 15°C, with a combined convection and radiation heat transfer coefficient of 20 W/m2·K. Determine if the plastic insulation on the ball will help or hurt heat transfer from the ball.

FIGURE P3-97