Physics

Fluid Mechanics and Hydraulics

361 Questions

Fluid mechanics and hydraulics questions address the principles of fluid flow, pipe resistance, and open channel dynamics. The topics include Bernoulli equation, Navier-Stokes equation, and hydrograph calculations. These concepts are crucial for civil and mechanical engineering competitive examinations.

Fluid flow equationsOpen channel flowPipe frictionHydraulic jumpHydrograph analysis

Fluid Mechanics and Hydraulics Questions

Multiple choice physics simple machine common machines terms related to machines introduction to simple machines

A pump ejects $12000\ kg$ of water at the speed of $4\ { m }/{ s }$ in $40\ second.$ Find the average rate at which the pump is working

  1. $2.4kw$
  2. $2.5kw$
  3. $2.3kw$
  4. $1.7kw$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$F=ma=12000\times \dfrac {4}{40}=1200\ N$
$A=F/m=1200/1200=1/10\ m/s^2$
$s=ut +\dfrac {1}{2}at^2=0+\dfrac {1}{2}\times \dfrac {1}{10}\times 40\times 40=80\ m$
then, $W=Fs=80\times 1200=96000\ J$
rate of working, $P=\dfrac {W}{t}$
$P=\dfrac {96000}{40}=2400W=2.4\ kW$
Multiple choice chemistry substances in the surroundings - their states and properties measurement of density properties of substances fundamental and derived units

A copper ball of density $8.6 g cm^{-3}$, 1 cm is diameter is immersed in oil of density $0.8cm^{-3}$ . if the ball remains suspended in oil in a uniform electric field of intensity $36000 NC^{-1} $acting in upward direction, what is the charge on the ball ? 

  1. $1.1 \mu C$
  2. $4.2 \mu C$
  3. $2.4 \mu C$
  4. $3.7 \mu C$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the ball to be suspended: electric force = weight - buoyant force. qE = ρ_ball V g - ρ_oil V g. q = (ρ_ball - ρ_oil)Vg/E. Volume of sphere = (4/3)πr³ = (4/3)π(0.5 cm)³. After unit conversions and calculation, q ≈ 1.1 μC. Option A is correct.

Multiple choice

2L of NS over 20 hours. Flow rate?

  1. 100 ml/hr

  2. 100 gtts/min

  3. 150 ml/hr

  4. 200 ml/hr
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To find the flow rate in ml/hr, divide the total volume by the total time. 2000 ml / 20 hours = 100 ml/hr.

Multiple choice

Viscosity is a measure of a fluid's?

  1. resistance to flow

  2. adhesive forces

  3. average kinetic NRG

  4. buoyancy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Viscosity is a fluid's resistance to flowing; high viscosity means it flows slowly, like honey.

Multiple choice physics pressure pressure in fluids pressure in liquids introduction to pressure

A hose shoots water straight up to a height of $2.5m$. The opening end of the hose an area of $0.75\ cm^{2}$. How much water will come out in one minute ?

  1. $21.5\ litre$
  2. $25\ litre$
  3. $30\ litre$
  4. $31.5\ litre$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using Bernoulli's equation, the velocity of water exiting the nozzle is v = sqrt(2gh) = sqrt(2 * 9.8 * 2.5) or using g = 9.8/10 approx. The volumetric flow rate is Q = A * v. Integrating over one minute gives the total volume, which computes to 31.5 liters.

Multiple choice physics pressure pressure in fluids pressure in liquids introduction to pressure

In cities water supply from an overhead tank to.the houses is done due to:

  1. difference in pressure

  2. gravitational force

  3. decrease of friction in pipes

  4. flow of liquid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The water in an overhead tank has higher gravitational potential to compared to water which finally flows out of the taps in the houses. 
The water moves due to this decrease in gravitational potential energy of water by flowing out of taps, or, the water is supplied by the gravitational force acting on water.

Multiple choice

Which property of a fluid describes its resistance to flow?

  1. Density

  2. Viscosity

  3. Surface tension

  4. Compressibility
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Viscosity is the property of a fluid that describes its resistance to flow. It is a measure of the internal friction between fluid particles.

Multiple choice

The Darcy-Weisbach equation is used to calculate:

  1. Pressure drop in a pipe.

  2. Flow rate in a pipe.

  3. Head loss in a pipe.

  4. Velocity of a fluid in a pipe.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Darcy-Weisbach equation is used to calculate the pressure drop in a pipe due to friction.

Multiple choice

The Moody diagram is a graphical representation of:

  1. Friction factor for pipe flow.

  2. Reynolds number for pipe flow.

  3. Pressure drop for pipe flow.

  4. Flow rate for pipe flow.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Moody diagram is a graphical representation of the friction factor for pipe flow as a function of the Reynolds number and relative roughness.

Multiple choice

In fluid mechanics, what is the relationship between pressure, velocity, and elevation in a flowing fluid?

  1. Bernoulli's Equation

  2. Navier-Stokes Equations

  3. Darcy-Weisbach Equation

  4. Hagen-Poiseuille Equation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bernoulli's Equation describes the relationship between pressure, velocity, and elevation in a flowing fluid, expressing the principle of conservation of energy.

Multiple choice

Which quantity represents the resistance of a fluid to flow?

  1. Viscosity

  2. Density

  3. Pressure

  4. Temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Viscosity is the property of a fluid that opposes the relative motion between its adjacent layers, causing internal friction.

Multiple choice

The rate of flow of a fluid through a pipe is determined by:

  1. Volumetric Flow Rate

  2. Mass Flow Rate

  3. Reynolds Number

  4. Froude Number
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Volumetric flow rate is the volume of fluid passing through a given cross-sectional area per unit time.

Multiple choice

The equation that describes the conservation of mass for an incompressible fluid is:

  1. Continuity Equation

  2. Navier-Stokes Equations

  3. Euler Equations

  4. Bernoulli's Equation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The continuity equation states that the mass of fluid entering a control volume must equal the mass leaving the control volume.