(20%) Problem 3: Lava at Th=825° C emerges from a volcano. A mass m= 75 kg of this lava flows at a constant velocity of

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20 Problem 3 Lava At Th 825 C Emerges From A Volcano A Mass M 75 Kg Of This Lava Flows At A Constant Velocity Of 1 (99.9 KiB) Viewed 43 times

(20%) Problem 3: Lava at Th=825° C emerges from a volcano. A mass m= 75 kg of this lava flows at a constant velocity of v= 0.47 m/s losing Q= 14250 J of heat every second to the surroundings. The lava flows a distance of 250 m before reaching the ocean. Assume that the temperature of the surroundings. Tsurr = 24° C is unaffected by the cooling of the lava. 17% Part (a) Calculate how long t in seconds it takes before this mass of lava reaches the ocean. ✓ Correct! 1 = 532 17% Part (b) Calculate the amount of heat ; in joules lost to the surroundings before this mass reaches the ocean. Q= 7.58 * 10(6) = 7580000 ✓ Correct! 17% Part (c) If the specific heat capacity of the lava in this process is c = 840J/kg °C, calculate the temperature of this mass of lava I in celsius just before it reaches the ocean. T = 699 ✓ Correct! *17% Part (d) Calculate entropy change of the surroundings 4S surr in J/K while the lava was moving toward the ocean. 4Scurr - 3598 X Attempts Remain *17% Part (e) Calculate the change in the entropy of the lava AS in joules per kelvin while the lava was moving toward the ocean. AS = 7679 X Attempts Remain Grade Summary Deductions 0 % Potential 100% > *17% Part (f) Did the cooling of the lava before it reached the ocean violate the second law of thermodynamics? No, because the total entropy change was greater than zero: (ASgurr +AS) 0. Yes, because the total entropy change was greater than zero: (ASgurr - AS) > 0 Yes, because the total entropy change was not zero: (ASgurr - AS) = 0 Yes, because the total entropy change was greater than zero: (ASgurr +AS) > 0 No, because the total entropy change was greater than zero: (ASgurr - A) > 0 Yes, because the total entropy change was not zero: (ASgurr +AS) = 0 O Yes, because the entropy change of the lava was negative: AS <0. Submissions Attempts remaining: 4 (0% per attempt) detailed view 1 0% Submit Hint Feedback I give up!