Question

Help with thermodynamics basics? Due at midnight, please help!

refer to a cup which contains water at room temperature. The cup is perfectly insulated so that no heal can transfer into or out of the cup. A small coffee cup heater inside the cup is used to transfer heat to the water. The water does not boil. If heat is transferred to the cup at a steady rate, which of the graphs below best represents the shape of the graph of the temperature of the water over time as the heat is transferred? Answer H if you think that none is correct. Each of the questions 17-19 describes a change in the situation described in question 16 (a heater in water in a perfectly insulated cup). For each question, choose the answer that best describes the temperature rise due to the change described. The temperature rise would be four times as large. two times as large. the same. half as large. one quarter as large. None of the above answers is correct. There is the same amount of water and twice the amount of heat is transferred. There is half as much water and the same amount of heat is transferred. The water is replaced by an equal mass of a liquid with half the specific heat capacity of water. The same amount of heat is transferred. refer to the same cup and heater described above but the cup initially contains a mixture of 50 grams of ice and 50 grams of water at 0 degree C. The cup is perfectly insulated so that no heat can transfer in or out. Room temperature is 25 degree C. A small coffee cup heater inside the cup allows heat to be transferred to the ice and water mixture. Heat is transferred at a steady rate and the mixture is stirred continuously so that the temperature is always uniform throughout the mixture. For each question below, choose the shape of the temperature-time graph from the graphs A through F on the previous page that best correspond to the temperature of the mixture during the time interval described. If you think no graph is appropriate, write H. (You may choose a graph more than once. The origin of the graphs does not necessarily represent 0 degree C.) Which graph could show a time interval when the ice is melting but there is still some ice in the water? Which graph could show a time interval when there is still some ice at the beginning of the time interval, but all the ice disappears before the end of the interval? Which graph could show a time interval when there is only water (the ice is completely melted before the time interval begins), but no boiling occurs during the interval? Which graph could show a time interval when the water is boiling during the entire time shown by the graph?

Answer 1

16.
Since water doesn't boil, temperature will never be constant.
Also initially, temperature will initially rise faster and later will become slow as it is reaching equilibrium
Answer: E

17.
Q = m*C* delta T
Is Q is doubled, delta T will double
Answer: B

18.
Q = m*C* delta T
Is m is halfed, delta T will double
Answer: B

19.
Q = m*C* delta T
Is C is halfed, delta T will double
Answer: B

Only 4 subparts at a time please