Mechanical Engineering Flashcards

In NCEES PE Mechanical practice, a shaft transmitting power P at angular velocity ω experiences a torque T equal to:

Answer: T = P/ω

Power is the product of torque and angular velocity: P = Tω, so T = P/ω.

According to NCEES PE Mechanical exam standards, the refrigeration cycle coefficient of performance (COP) is defined as:

Answer: Heat absorbed from cold reservoir divided by net work input

COP for a refrigerator = QL/W_net: the desired effect (heat removed from cold space) divided by the work input.

In NCEES Mechanical dynamics, the natural frequency of a simple spring-mass system (undamped) is:

Answer: ωn = √(k/m)

The natural frequency ωn = √(k/m) in rad/s for an undamped single-degree-of-freedom system.

For the NCEES PE Mechanical exam, the Rankine cycle efficiency is improved most effectively by:

Answer: Lowering condenser pressure or increasing boiler temperature/pressure

Rankine cycle efficiency increases by raising the maximum cycle temperature/pressure or lowering the minimum (condenser) pressure.

In NCEES PE Mechanical problems, the drag force on an object moving through a fluid is expressed as:

Answer: FD = ½ρV²ACD

Drag force FD = ½ρV²ACD, where CD is the drag coefficient, A is reference area, and ρ is fluid density.

Which type of gear is used to transmit power between parallel shafts and is most commonly encountered in NCEES PE Mechanical exam problems?

Answer: Spur gear

Spur gears transmit power between parallel shafts and are the most fundamental gear type covered in NCEES PE Mechanical.