A 200 g aluminum cup contains 800 g of water in thermalequilibrium with the cup

Question

A 200 g aluminum cup contains 800 g of water in thermalequilibrium with the cup at 80° C. The combination of cupand water is cooled uniformly so that the temperature decreases by1.5° C per minute. At what rate is energy being removed?Express your answer in watts.

The answer is 88 W, but I have no idea how to get it that way. Ihave tried working things backwards to see if it would help but ithas not. Obviously, I am completely on the wrong track with thisproblem. Can someone break it down and explain it to me.

Explanation / Answer

mass of aluminium M = 200 g = 0.2 kg mass of water m = 800 g = 0.8 kg Decrease in temperature in 1 minute dt = 1.5o C Energy removed in one minute Q = M C dt + m c dt where C = specific heat of aluminium = 900 J / kg o C            c = specific heat of water = 4186 J / kg o C substitue values we get Q value So, rate of energy removed = Q/ 60 substitue values wegetanswer            

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