A small copper ball of 5 mm diameter at 500 K is dropped into an oil bath whose temperature is 300 K. the thermal conductivity of copper is 400 W/m. K, its density 9000 kg/m3, and its specific heat 385 J/kg.K. if the heat transfer coefficient is 250 W/m2K and lumped analysis is assumed to be valid, the rate of fall of the temperature of the ball at the beginning of cooling will be, in K/s. A. 8.7 B. 13.9 C. 17.3 D. 27.7
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