A 50 cm long cylindrical flask with inner and outer diameters 4 cm and 8 cm is completely filled with ice. The outside temperature is a constant 30°C. The thermal conductivity of the flask is 0.693 W/

Question

A 50 cm long cylindrical flask with inner and outer diameters 4 cm and 8 cm is completely filled with ice. The outside temperature is a constant 30°C. The thermal conductivity of the flask is 0.693 W/m°C and L i ce ​ = 80 cal/g (take 1 cal = 4.2 J).

TestHub · Accepted Answer

P = ln ( r 2 ​ / r 1 ​ ) 2 πk L Δ T ​ = ln 2 2 π ( 0.693 ) ( 0.5 ) ( 30 ) ​ = 30 π W = 94.2 W (A). L = 3.36 × 1 0 5 J/kg, so m ˙ = 3.36 × 1 0 5 30 π ​ = 11200 π ​ kg/s (B). C and D are twice these.

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