Which of the following is an example of something not allowed by the second law of thermodynamics? Indicate true or false.
1.All refrigerators can be made perfect
2.A spoon in a hot drink spontaneously stirring the drink
3.All the molecules suddenly moving to one place in a room
4.A perfect refrigerator
Moving heat from a cold place to a hotter place with the use of some work
Nevermind I got it =]
II'm not sure what is meant by a "perfect" refrigerator. It is possible to have a refrigerator what does not require work. The use an external heat source. See
http://www.dometicusa.com/refrigerators.php
Stirring a cup requires energy, and wuld violate the first law.
Molecules CAN gather in part of a room, but the probability is infinitesimal.
The correct answer is:
3. All the molecules suddenly moving to one place in a room
This is an example of a violation of the second law of thermodynamics. According to the second law, the entropy of an isolated system tends to increase over time. In this case, all the molecules suddenly moving to one place in a room would lead to a decrease in entropy, which is not allowed by the second law. Therefore, the statement is false.
To determine which of the options is an example of something not allowed by the second law of thermodynamics, let's analyze each option one by one:
1. All refrigerators can be made perfect - False
This statement is false because the second law of thermodynamics states that it is impossible to build a device (including refrigerators) that operates in a cycle and extracts heat from a cold place to a hotter place without the input of external energy or work.
2. A spoon in a hot drink spontaneously stirring the drink - False
This statement is also false because the second law of thermodynamics states that in a closed system, heat will naturally flow from a hotter object to a cooler one. In this case, the spoon transfers heat from the hot drink to itself, not the other way around.
3. All the molecules suddenly moving to one place in a room - False
This statement is false because the second law of thermodynamics also suggests that in a closed system, the random motion of molecules (entropy) tends to increase rather than decrease. Therefore, it is highly unlikely for all the molecules in a room to suddenly move to one place without any external intervention.
4. A perfect refrigerator - False
The idea of a perfect refrigerator contradicts the principles of the second law of thermodynamics. As mentioned earlier, the second law states that it is impossible to build a device that extracts heat from a cold place to a hotter place without external energy or work. Therefore, a perfect refrigerator, by definition, violates this law.
Out of the given options, none of them are examples of something not allowed by the second law of thermodynamics. However, the last option (Moving heat from a cold place to a hotter place with the use of some work) aligns with the concept of the second law. This process requires external work to transfer heat from a cold place to a hotter place, which is permissible according to the second law of thermodynamics.