Forced-convection heat transfer from an isolated sphere 

(a) A solid sphere 1 in. in diameter is placed in an otherwise undisturbed air stream, which approaches at a velocity of 100 ft/s, a pressure of I arm, and a temperature of 100°F. The sphere surface is maintained at 200°F by means of an imbedded electric heating coil. What must be the rate of electrical heating in cal/s to maintain the stated conditions? Neglect radiation, and use Eq. 14.4-5. 

(b) Repeat the problem in (a), but use Eq. 14.4-6