Mechanical Engineering - MCQ Practice Questions

Entropy change for a reversible isothermal process where heat Q is absorbed is:

The dryness fraction of a wet steam sample is 0.8. If specific enthalpy of saturated liquid and vapor at a pressure are 500 kJ/kg and 2700 kJ/kg respectively, the specific enthalpy of the mixture is:

Which of the following processes follows the path PV^n = constant?

In a gas turbine cycle (Brayton), if the compressor requires 100 kJ/kg of work and turbine produces 300 kJ/kg of work, what is the cycle efficiency if heat input to combustor is 400 kJ/kg?

A rigid tank contains 2 kg of nitrogen gas at 100 kPa and 25°C. Heat is added until the pressure reaches 500 kPa. Assuming constant specific heats (Cv = 0.745 kJ/kg·K for N₂), what is the final temperature of the gas?

A pump delivers 0.05 m³/s of water. If the pipe diameter is 0.1 m, the velocity of flow is:

The Darcy friction factor for fully developed laminar flow in a pipe depends on:

Water flows through a horizontal pipe with diameter 0.05 m at a velocity of 2 m/s. The volumetric flow rate is:

The Mach number is the ratio of:

For turbulent flow in pipes, the Colebrook-White equation is used to find the friction factor. Which of the following is NOT an input parameter?

A fluid element has shear stress τ = 0.5 Pa and velocity gradient du/dy = 10 s⁻¹. The dynamic viscosity of the fluid is:

The Reynolds number for flow in a circular pipe is given by Re = ρVD/μ. If the flow transitions from laminar to turbulent at Re ≈ 2300, then for a pipe with D = 0.025 m and V = 1.5 m/s (ρ = 1000 kg/m³, μ = 0.001 N·s/m²), the flow regime is:

Which of the following is a dimensionless number used in fluid mechanics that compares inertial forces to surface tension forces?

A venturi meter is used to measure fluid flow rate. The principle it operates on is:

The major loss in pipe flow (Darcy-Weisbach equation: hf = f(L/D)(V²/2g)) is primarily due to:

In a pitot tube, the stagnation pressure and static pressure are measured. The velocity at the measurement point is:

A jet of water impinges on a flat plate perpendicular to its surface. If jet velocity is 10 m/s and jet area is 0.01 m², the force on the plate is approximately:

In a U-tube manometer with mercury, if one leg shows 50 mm height difference, the pressure difference is:

For a turbulent flow in pipes, the friction factor f in the Darcy-Weisbach equation depends primarily on:

A convergent-divergent nozzle (De Laval nozzle) accelerates gas to supersonic speeds. The throat area compared to exit area is: