Two identical objects are in thermal contact. One is at a high temperature (T-hot) and the...
Two identical objects are in thermal contact. One is at a high temperature (T-hot) and the other is at a cool temperature (T-cool). Assume that this system is isolated, i.e. there is no interaction with the surroundings. Using the thermodynamic definition of entropy, explain why heat always flows from T-hot to T-cool, and never the other way around.
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Two identical objects are in thermal contact. One is at a high
temperature (T-hot) and the...
When two objects are in thermal contact heat energy is transferred from the hot to the...
When two objects are in thermal contact heat energy is transferred from the hot to the cold object until the temperature of both becomes equal (i.e., the objects are in thermal equilibrium). Suppose you pour 20-gram milk at 200C into a cup of 80-gram tea at 920C. Assume the specific heat of tea is 4.2 J/gram.0K and that of milk is 3.9 J/gram.0K Assuming no heat is lost into the surrounding air what is the temperature of the tea and...
Two objects are maintained at constant temperatures, one hot and one cold. Two identical bars can...
Two objects are maintained at constant temperatures, one hot and one cold. Two identical bars can be attached end to end, as in part a of the drawing, or one on top of the other, as in part b. When either of these arrangements is placed between the hot and the cold objects for the same amount of time, heat Q flows from left to right. Find the ratio Qa/Qb. (b) Qa/Qb= Number i Units
2. Consider a macroscopic system of two blocks that are in thermal contact. The two-block system ...
2. Consider a macroscopic system of two blocks that are in thermal contact. The two-block system is isolated from the rest of the universe. Initially, a hotter block is at a temperature TH and a colder block is at a temperature Tc. In the final state of the system, the two blocks are at the same intermediate temperature T. Compare the following quantities for the matal state and final state: Entropy for the block that starts at TH Sf> Si...
Two initially separated objects, make thermal contact, m_1, c_1 and T_1 are respectively the mass, specific...
Two initially separated objects, make thermal contact, m_1, c_1 and T_1 are respectively the mass, specific heat and temperature of the first object and m_2, c_2 and T_2 are respectively the corresponding of the second object. The initial temperatures are T_20 <T_10. While body 1 slowly cools, 2 heats up slowly. a) Calculate T_2 (T_1) b) Find the change in deltropy entropy as a function of T_1 c) show that deltaS is a maximum when both bodies reach thermal equilibrium
Problem 8: Two amounts of salt water at different temperatures are brought into thermal contact with...
Problem 8: Two amounts of salt water at different temperatures are brought into thermal contact with each other and mixed thoroughly. The first amount of water has mass m, = 0.302 kg and its initial temperature is T, = 7.61 °C. The second has a mass of m2 = 0.873 kg and an initial temperature of T2 = 34.5 °C. Assume that the system is isolated. Let the specific heat of the water at this salinity to be Cw=0.84 kcal...
Two containers, one at 305 K and the other at 295 K, are placed in contact...
Two containers, one at 305 K and the other at 295 K, are placed in contact with each other. a. 1 J of heat flows from the hot container to the cold container. Find the change in entropy of the hot container and the cold container, and of the whole system (hot + cold container together). Does this process violate the second law of thermodynamics? b. 1 J of heat flows from the cold container to the hot container. Find...
1. Hot air rises - this causes upward heat transfer and is one of the most...
1. Hot air rises - this causes upward heat transfer and is one of the most familiar forms of convection. Why does air cool as it rises this way? 2. (H16.17) Since all objects emit energy to their surroundings, why don’t the temperatures of all objects continuously decrease? 3. (H16.25) Does Newton’s law of cooling apply to warming a well as to cooling? 4. (H17.4) Why is evaporation a cooling process? 5. (H17.19) When will water boil at a temperature...
Questions See the last page for thermodynamic constants that may be need to answer questions and...
Questions See the last page for thermodynamic constants that may be need to answer questions and problems. 1. (2) Fully explain why the following sentence is incorrect (i.e. use some terminology incorrectly). "The sun heated the sidewalk and now the sidewalk has a lot of heat." 2. (4) A piece of iron and a piece of copper with equal masses but different temperatures are put in thermal contact and isolated from their surroundings. They exchange heat until they reach thermal...
Question 2 [Total Marks 25 High Temperature Solar Thermal Systems a) Describe the principle of operation of a central r...
Question 2 [Total Marks 25 High Temperature Solar Thermal Systems a) Describe the principle of operation of a central receiver concentrating solar thermal system Include a discussion of the method of collecting sunlight, working fluid, generating electricity and storage. Include appropriate diagram(s) in your description 10 Marks Describe the key differences between solar trough and parabolic dish solar thermal b) collectors. Why is the receiver for a parabolic dish located a long way above the rim of the collector, while...
2. In lecture, we have derived the thermodynamic definition of temperature, OS In this problem, you...
2. In lecture, we have derived the thermodynamic definition of temperature, OS In this problem, you will examine what happens to the entropy (i.e., the number of microstates) when two systems with different temperatures interact and exchange energy. The result foreshadows what we will later get to know as the second law of thermodynamics (a) *D1* A system at temperature and energy E absorbs a small amount of energy ΔΕ. Show that the change in entropy is approximately equal to...
Two objects are maintained at constant temperatures, one hot and one cold. Two identical bars can be attached end to end, as in part a of the drawing, or one on top of the other, as in part b. When either of these arrangements is placed between the hot and the cold objects for the same amount of time, heat Q flows from left to right. Find the ratio Qa/Qb. (b) Qa/Qb= Number i Units
2. Consider a macroscopic system of two blocks that are in thermal contact. The two-block system is isolated from the rest of the universe. Initially, a hotter block is at a temperature TH and a colder block is at a temperature Tc. In the final state of the system, the two blocks are at the same intermediate temperature T. Compare the following quantities for the matal state and final state: Entropy for the block that starts at TH Sf> Si...
Problem 8: Two amounts of salt water at different temperatures are brought into thermal contact with each other and mixed thoroughly. The first amount of water has mass m, = 0.302 kg and its initial temperature is T, = 7.61 °C. The second has a mass of m2 = 0.873 kg and an initial temperature of T2 = 34.5 °C. Assume that the system is isolated. Let the specific heat of the water at this salinity to be Cw=0.84 kcal...
Questions See the last page for thermodynamic constants that may be need to answer questions and problems. 1. (2) Fully explain why the following sentence is incorrect (i.e. use some terminology incorrectly). "The sun heated the sidewalk and now the sidewalk has a lot of heat." 2. (4) A piece of iron and a piece of copper with equal masses but different temperatures are put in thermal contact and isolated from their surroundings. They exchange heat until they reach thermal...
Question 2 [Total Marks 25 High Temperature Solar Thermal Systems a) Describe the principle of operation of a central receiver concentrating solar thermal system Include a discussion of the method of collecting sunlight, working fluid, generating electricity and storage. Include appropriate diagram(s) in your description 10 Marks Describe the key differences between solar trough and parabolic dish solar thermal b) collectors. Why is the receiver for a parabolic dish located a long way above the rim of the collector, while...
2. In lecture, we have derived the thermodynamic definition of temperature, OS In this problem, you will examine what happens to the entropy (i.e., the number of microstates) when two systems with different temperatures interact and exchange energy. The result foreshadows what we will later get to know as the second law of thermodynamics (a) *D1* A system at temperature and energy E absorbs a small amount of energy ΔΕ. Show that the change in entropy is approximately equal to...
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