A metal sphere 25 mm in diameter was heated to 95°C, and then suspended in air at 22°C. The mass density of the metal is 7920 kg/m3, its specific heat at 30°C is cp = 500 J/(kg.°C), and its thermal conductivity at 30°C is 400 W/(m.oC). The following sphere temperature data were measured as the sphere cooled.

a. Assume that the sphere's heat loss rate is due entirely to convection. Estimate the convection coefficient h.
b. Compute the Biot number and discuss the accuracy of the lumped-parameter model used in part (a).
c. Discuss whether some of the heat loss rate could be due to radiation. Give a numerical reason for your answer.

Ms) T C) (s) TCC) r(s) TCC) 0 95 120 85 540 67 15 93 135 84600 65 30 92 180 82 660 62 45 90 240 79 720 61 60 89 300 76 780 59 75 88 360 73 840 57 90 87 42071 900 56 105 86 48069 960 54