BME

1. A
2. C
3. A
4. B
5. B
6. C
7. B
8. B
9. B
10. B
11. C
12. C
13. B
14. C
15. D
16. B
17. C
18. A
19. A
20. B
21. B
22. A
23. C
24. C
25. A
26. B
27. B
28. B
29. A
30. C

Sample BME - Bachelor of Mechanical Engineering Practice Questions

Try these questions from our free BME - Bachelor of Mechanical Engineering practice tests. The correct answer and an explanation follow each question.

1. In a Mohr's circle construction, the center of the circle lies at:

   • A. (σ_x, τ_xy)
   • B. ((σ_x + σ_y)/2, 0)
   • C. ((σ_x − σ_y)/2, τ_xy)
   • D. ((σ_x + σ_y)/2, τ_xy)

   Answer: B. ((σ_x + σ_y)/2, 0)

   The center of Mohr's circle is at the average normal stress ((σ_x + σ_y)/2, 0) on the σ–τ plane.

2. In a Brayton cycle, increasing the compressor pressure ratio (up to the optimal value) generally:

   • A. Decreases thermal efficiency
   • B. Has no effect on efficiency
   • C. Increases thermal efficiency
   • D. Decreases net work output only

   Answer: C. Increases thermal efficiency

   Higher pressure ratio increases the thermal efficiency of the Brayton cycle because more compression raises the average temperature of heat addition.

3. Creep in metals at elevated temperatures is best described as:

   • A. Instantaneous plastic deformation upon loading
   • B. Time-dependent permanent deformation under constant stress
   • C. Elastic deformation recovered upon unloading
   • D. Fatigue damage accumulated over cyclic loading

   Answer: B. Time-dependent permanent deformation under constant stress

   Creep is the slow, time-dependent plastic deformation that occurs under sustained stress, especially above ~0.4 T_m (homologous temperature).

4. What is cavitation in a centrifugal pump?

   • A. Formation and collapse of vapor bubbles due to local pressure drop below vapor pressure
   • B. Blockage of impeller by solid particles
   • C. Reverse flow through the pump at low speeds
   • D. Air entrainment through the suction flange

   Answer: A. Formation and collapse of vapor bubbles due to local pressure drop below vapor pressure

   Cavitation occurs when local pressure falls below the liquid's vapor pressure, causing vapor bubbles that implode violently and damage pump components.

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