A metallic sphere having radius 0.08 m and mass m = 10 kg is heated to a temperature of 227°C and suspended inside a box ….

Q: A metallic sphere having radius 0.08 m and mass m = 10 kg is heated to a temperature of 227°C and suspended inside a box whose walls are at a temperature of 27°C. The maximum rate at which its temperature will fall is (take e = 1, Stefan’s constant σ = 5.8 × 10-8 Wm² K-4 and specific heat of the metal = 90 cal/kg/deg J = 4.2 J/cal)

(a) 0.055°C/s

(b) 0.066°C/s

(c) 0.044°C/s

(d) 0.03°C/s

Ans: (b)

 

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