Consider a 5-mm-diameter spherical ball at 50 °C which is covered by a 1-mm-thick plastic insulation (k = 0.13 W/m · °C). The ball is exposed to a medium at 15 °C, with a combined convection and radiation heat transfer coefficient of 20 W/m2· °C. Determine if the plastic insulation on the ball will help or hurt heat transfer from the ball.