Heat and Thermodynamics II - SS1 Physics Past Questions and Answers - page 4
The second law of thermodynamics is concerned with:
Energy conservation
Heat transfer
Entropy increase
Mass conservation
The second law of thermodynamics states that in a closed system, the entropy of the system:
Decreases
Remains constant
Increases
Fluctuates
The second law of thermodynamics introduces the concept of:
Internal energy
Heat capacity
Enthalpy
Entropy
Explain the first law of thermodynamics in detail. How does it relate to the principle of energy conservation?
The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed in an isolated system. It can only be transferred or transformed from one form to another. This law is based on the principle of energy conservation, which states that the total energy of a closed system remains constant over time. According to the first law, the change in internal energy of a system is equal to the heat added to the system minus the work done by the system on its surroundings.
Discuss the second law of thermodynamics and its implications. What is the concept of entropy, and how does it relate to the second law?
The second law of thermodynamics deals with the direction of natural processes and the concept of entropy. It states that in an isolated system, the total entropy of the system and its surroundings always increases or remains constant. Entropy is a measure of the disorder or randomness in a system. The second law implies that spontaneous processes tend to increase the overall disorder or entropy of the universe. It also provides a criterion for the direction of heat transfer, stating that heat flows spontaneously from regions of higher temperature to regions of lower temperature.
Which of the following best describes a heat engine?
A device that converts heat into mechanical work
A device that converts mechanical work into heat
A device that converts mechanical work into electrical energy
A device that converts electrical energy into mechanical work
Which law of thermodynamics sets an upper limit on the efficiency of a heat engine?
First law of thermodynamics
Second law of thermodynamics
Zeroth law of thermodynamics
Third law of thermodynamics
Efficiency of a heat engine is defined as:
Work input divided by work output
Work output divided by work input
Heat input divided by heat output
Heat output divided by heat input
The Carnot efficiency of a heat engine depends on:
The temperature of the heat source
The temperature of the heat sink
Both the temperature of the heat source and the heat sink
Neither the temperature of the heat source nor the heat sink
Which statement is true regarding the efficiency of a heat engine?
It can be greater than 100%
It can be equal to 100%
It can be less than 100%
It is always equal to zero