Mechanical Engineering - MCQ Practice Questions

A horizontal pipe of diameter 50 mm carries water at 2 m/s. If the pipe length is 100 m and friction factor f = 0.04, calculate the head loss using Darcy-Weisbach equation.

In a pitot tube measurement, the stagnation pressure is 105.5 kPa and static pressure is 100 kPa. What is the velocity of the fluid? (ρ = 1000 kg/m³)

A 300 mm diameter pipe reduces to 150 mm diameter. If velocity in the larger pipe is 1.5 m/s, what is the velocity in the smaller pipe, assuming incompressible flow?

A submerged orifice discharges water under a head of 4 m. The coefficient of discharge is 0.62. If the orifice area is 0.01 m², what is the discharge rate?

For laminar flow in a circular pipe, the Hagen-Poiseuille equation gives discharge as Q = πΔPd⁴/(128μL). This is valid for Reynolds number:

A pump delivers 0.05 m³/s of water against a head of 25 m. If the pump efficiency is 80%, what is the required power input?

In a convergent nozzle, which property increases as the flow accelerates?

A turbine receives water at 3.5 m³/s with a head of 45 m. If the turbine efficiency is 85%, what is the power output?

For a weir with discharge Q = C_w × L × H^($\frac{3}{2}$), if the length is doubled and head is halved, the new discharge becomes:

A jet of water with velocity 20 m/s hits a flat plate perpendicularly. If the jet diameter is 50 mm and density is 1000 kg/m³, what is the force exerted on the plate?

Which dimensionless number is used to characterize the relative importance of gravity and inertial forces in open channel flow?

A 100 mm diameter pipe contains a 90° elbow. If water flows at 3 m/s and minor loss coefficient K = 0.9, what is the head loss?

In compressible flow, if Mach number M = 1.2, the flow is classified as:

A vertical pipe of diameter 40 mm has water flowing upward at 2.5 m/s. If the friction factor is 0.035 and pipe length is 50 m, what is the total head loss (friction + elevation)?

A circular jet impinges on a 45° inclined flat plate and splits equally. If jet velocity is 15 m/s and diameter is 30 mm, what is the magnitude of the resultant force?

In a venturi meter, if the area ratio is 4:1 and the pressure difference is 8 kPa, what is the velocity in the throat? (ρ_water = 1000 kg/m³)

A horizontal jet of 0.02 m² cross-section with velocity 8 m/s strikes a curved vane and is deflected 60°. What is the force on the vane in the direction of jet?

For a rectangular open channel with width 5 m carrying 12 m³/s of water, if the critical depth is 1.5 m, what is the critical velocity?

In fluid mechanics, which of the following statements about Pascal's law is correct?

The continuity equation for incompressible flow states that A₁V₁ = A₂V₂. If water flows through a pipe that narrows from 100 mm to 50 mm diameter, the velocity ratio V₂/V₁ is: