Physics

Fluid Mechanics

673 Questions

Fluid mechanics is a core physics topic that evaluates the principles of liquid pressure, buoyancy, density, and viscosity through complex numerical problems. The questions require calculating the volume of submerged objects, understanding hydraulic jumps, and applying fundamental fluid statics principles. It is a highly scoring subject for candidates preparing for technical and engineering competitive exams.

Liquid pressure and depthBuoyancy and densityVolume expansionHydraulic jump calculationsSurface tension mechanics

Fluid Mechanics Questions

Multiple choice

The buoyant force is an upward force exerted by a fluid on an object immersed in it.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The buoyant force is equal to the weight of the fluid displaced by the object.

Multiple choice

What is the name of Archimedes' principle?

  1. Buoyancy

  2. Leverage

  3. Hydrostatics

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

Archimedes' principle states that an object submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object.

Multiple choice

Which of the following is NOT a type of flow resistance encountered in external flows?

  1. Skin friction

  2. Form drag

  3. Wave drag

  4. Induced drag
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Induced drag is a type of aerodynamic drag generated by the lift produced by an airfoil. It is not encountered in external flows in the context of fluid mechanics.

Multiple choice

In fluid dynamics, the force acting on a fluid particle due to the pressure gradient is described by:

  1. Bernoulli's equation

  2. Navier-Stokes equations

  3. Euler's equation

  4. Poiseuille's equation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Euler's equation is a fundamental equation in fluid dynamics that describes the force acting on a fluid particle due to the pressure gradient.

Multiple choice

What is the dimension of surface tension?

  1. $\frac{M}{L^2}$
  2. $\frac{ML}{T}$
  3. $\frac{L^2}{T^2}$
  4. $\frac{ML^2}{T^2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The dimension of surface tension is $\frac{M}{L^2}$.

Multiple choice

What is the dimensionless number used to characterize the relative importance of inertial forces to viscous forces in fluid flow?

  1. Reynolds number

  2. Prandtl number

  3. Mach number

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

The Reynolds number is a dimensionless number that compares the inertial forces to the viscous forces acting on a fluid. It is used to determine whether the flow is laminar or turbulent.

Multiple choice

Which force is responsible for the drag experienced by an object moving through a fluid?

  1. Gravity

  2. Friction

  3. Buoyancy

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

Drag is the force that opposes the motion of an object moving through a fluid. It is caused by the interaction between the fluid and the surface of the object.

Multiple choice

What is the dimensionless number used to characterize the relative importance of inertial forces to gravitational forces in fluid flow?

  1. Reynolds number

  2. Prandtl number

  3. Mach number

  4. Froude number
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The Froude number is a dimensionless number that compares the inertial forces to the gravitational forces acting on a fluid. It is used to determine whether the flow is subcritical or supercritical.

Multiple choice

Which force is responsible for the buoyant force experienced by an object submerged in a fluid?

  1. Gravity

  2. Friction

  3. Buoyancy

  4. Pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Buoyancy is the upward force exerted by a fluid on an object submerged in it. It is equal to the weight of the fluid displaced by the object.

Multiple choice

What is the dimensionless number used to characterize the relative importance of inertial forces to elastic forces in fluid flow?

  1. Reynolds number

  2. Prandtl number

  3. Mach number

  4. Elasticity number
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The Elasticity number is a dimensionless number that compares the inertial forces to the elastic forces acting on a fluid. It is used to determine whether the flow is elastic or inelastic.

Multiple choice

Which CFD technique is commonly used to simulate flows with large density variations?

  1. Compressible flow solver

  2. Incompressible flow solver

  3. Isothermal flow solver

  4. Non-isothermal flow solver
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The compressible flow solver is commonly used to simulate flows with large density variations, where the density is treated as a variable.

Multiple choice

According to Pascal's Law, how does pressure applied to a fluid in a closed container behave?

  1. It remains constant throughout the fluid

  2. It decreases with depth

  3. It increases with depth

  4. It varies randomly
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pascal's Law states that pressure applied to a fluid in a closed container is transmitted equally to every point in the fluid. This means that the pressure remains constant throughout the fluid, regardless of depth or location.

Multiple choice

What is the relationship between pressure and depth in a fluid?

  1. Pressure is directly proportional to depth

  2. Pressure is inversely proportional to depth

  3. Pressure is independent of depth

  4. Pressure varies randomly with depth
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a fluid at rest, pressure increases linearly with depth. This relationship is known as hydrostatic pressure, and it is expressed by the equation P = ρgh, where P is pressure, ρ is fluid density, g is acceleration due to gravity, and h is depth.

Multiple choice

What is the principle of buoyancy?

  1. An object in a fluid experiences an upward force equal to its weight

  2. An object in a fluid experiences a downward force equal to its weight

  3. An object in a fluid experiences no force

  4. An object in a fluid experiences a force proportional to its volume
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of buoyancy states that an object submerged in a fluid experiences an upward force equal to the weight of the fluid displaced by the object. This force is known as buoyant force, and it is responsible for the ability of objects to float or sink in a fluid.

Multiple choice

What determines whether an object will float or sink in a fluid?

  1. The object's density

  2. The object's weight

  3. The object's shape

  4. The object's size
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An object will float if its average density is less than the density of the fluid. Conversely, an object will sink if its average density is greater than the density of the fluid. The object's weight, shape, and size do not directly determine whether it will float or sink.