NCEES Mechanical Engineering PE Exam

Question 1

On the NCEES PE Mechanical exam, which thermodynamic cycle best describes the operation of a steam power plant?

Accepted Answer

Rankine cycle

Answer

The Rankine cycle (with water/steam as the working fluid undergoing phase changes) is the standard thermodynamic model for steam power plants.

Question 2

In the NCEES PE Mechanical exam, what does the 'coefficient of performance (COP)' of a refrigeration cycle represent?

Accepted Answer

The ratio of useful refrigeration effect to work input

Answer

COP of a refrigerator equals the heat absorbed at the evaporator (QL) divided by the net work input (Win), measuring how effectively work is converted to cooling.

Question 3

For the NCEES PE Mechanical exam, which equation defines the steady-flow energy equation (SFEE) for an open system?

Accepted Answer

Q̇ - Ẇ = ṁ[(h2 - h1) + (V2² - V1²)/2 + g(z2 - z1)]

Answer

The SFEE for steady open systems accounts for heat transfer, work, and changes in enthalpy, kinetic energy, and potential energy of the flowing fluid.

Question 4

On the NCEES PE Mechanical exam, what is the significance of the 'isentropic efficiency' of a turbine?

Accepted Answer

It is the ratio of actual work output to ideal isentropic work output

Answer

Isentropic (turbine) efficiency compares actual work extracted to the theoretical maximum work obtainable in a reversible adiabatic (isentropic) process.

Question 5

In the NCEES PE Mechanical exam, which law states that the total pressure of a gas mixture equals the sum of partial pressures of its components?

Accepted Answer

Dalton's law of partial pressures

Answer

Dalton's law states that for an ideal gas mixture, the total pressure equals the sum of the pressures each component gas would exert if it alone occupied the volume.

NCEES National Council of Examiners for Engineering and Surveying Practice Practice Test

NCEES National Council of Examiners for Engineering and Surveying Practice Practice Test

NCEES Mechanical Engineering PE Exam