Mechanical Board Exam Review Question: Thermodynamics Elements (ANSWERS)

Here are the answers to the questions posted yesterday on the topic THERMODYNAMICS. Please feel free to comment or ask for clarifications.
1. The state of a simple substance can be defined by at least how many properties (e.g. pressure, mass, temperature, density)?
ANSWER: B. TWO

2. The ability of a heat engine to convert the supplied heat to work is referred to as…
ANSWER: A. THERMAL EFFICIENCY

3. To increase the efficiency of a Carnot cycle…
ANSWER: C. BOTH a AND b
Increasing the max temperature and decreasing the min temperature will increase the area in the T-s diagram meaning more work for the same heat input.

4. The area under the curve of the process plotted in the p-V diagram corresponds to…
ANSWER: B. WORK NON-FLOW (INTEGRAL OF pdV)

5. The value of n, in the equation PVn=C when the process is isothermal?
ANSWER: A. 1

6. The value of n, in the equation PVn=C when the process is isometric?
ANSWER: C. INFINITY

7. In the T-s diagram, the area under the process curve corresponds to…
ANSWER: A. HEAT OF THE PROCESS (Q)

8. What law of thermodynamics introduced the concept of entropy?
ANSWER: B. SECOND LAW
The second law of thermodynamics explains irreversibility of the process and introduced the concept of entropy.

9. A device that converts heat energy to shaft work.
ANSWER: B. HEAT ENGINE

10. A thermodynamic process characterized by a straight vertical line in the T-s diagram.
ANSWER: B. ADIABATIC PROCESS
The horizontal axis of the T-s diagram is entropy, so straight vertical line is a constant entropy process (adiabatic or reversible isentropic).