Thermodynamics Questions and Answers – Displacement Work and Indicator Diagram

This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Displacement Work and Indicator Diagram”.

1. Macroscopic properties p and V are significant only for
a) equilibrium states
b) non-equilibrium states
c) depends on the state
d) none of the mentioned

Explanation: This is true for at any intermediate point in the travel of piston.

2. In a cylinder, infinitesimal amount of work done by the gas on piston is given by
a) F*dl
b) p*a*dl
c) p*dV
d) all of the mentioned

Explanation: F=p*a and work equals force multiplied by displacement.

3. For a constant pressure process, work done is
a) zero
b) p*(V2-V1)
c) p1*V1*ln(V2/V1)
d) none of the mentioned

Explanation: Work done in a process is given by the area under p-dV graph.

4. For a constant volume process, work done is
a) zero
b) p*(V2-V1)
c) p1*V1*ln(V2/V1)
d) none of the mentioned

Explanation: Work done in a process is zero since volume remains constant.

5. For a process in which pV=C, work done is
a) zero
b) p*(V2-V1)
c) p1*V1*ln(V2/V1)
d) none of the mentioned

Explanation: Work done is given by integral of (p*dV) from V1 to V2.

6. The area of the indicator diagram represents the magnitude of the
a) net heat transfer by the system
b) net work done on the system
c) net work done by the system
d) none of the mentioned

Explanation: It is the work done in one engine cycle.

7. For Pm=(Ad/Ld)*K, which of the following is true?
a) Pm=mean effective pressure
b) Ad and Ld are area of diagram and length of diagram respectively
c) K id the indicator spring constant
d) all of the mentioned

Explanation: This formula comes from the indicator diagram.

8. For a two-stroke engine, work done in one minute is given by
a) PmALN
b) PmALN/2
c) 2PmALN
d) none of the mentioned

Explanation: In a two-stroke cycle, the engine cycle is completed in two strokes of the piston.

9. The power available at crankshaft is always _____ indicated power.
a) more
b) less
c) equal
d) none of the mentioned

Explanation: Due to friction.

10. Mechanical efficiency of engine is given by
a) IP/BP
b) 1/(BP*IP)
c) (BP*IP)
d) BP/IP

Explanation: Brake power is less than indicated power and mechanical efficiency is given by BP/IP.

11. An engine is said to be double-acting, if the working fluid is made to work on both sides of the piston.
a) true
b) false

Explanation: Such an engine develops twice the amount of work developed in a single-acting engine.

Sanfoundry Global Education & Learning Series – Thermodynamics.
To practice all areas of Thermodynamics, here is complete set of 1000+ Multiple Choice Questions and Answers.

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