Physics

Fluid Mechanics

637 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 principle of buoyancy states that:

  1. An object immersed in a fluid experiences an upward force equal to the weight of the fluid displaced by the object.

  2. An object immersed in a fluid experiences a downward force equal to the weight of the fluid displaced by the object.

  3. An object immersed in a fluid experiences no force.

  4. An object immersed in a fluid experiences a force equal to the difference between the weight of the object and the weight of the fluid displaced by the object.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of buoyancy states that an object immersed in a fluid experiences an upward force equal to the weight of the fluid displaced by the object.

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 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

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.

Multiple choice

What is the equation for calculating the buoyant force acting on an object submerged in a fluid?

  1. F_b = ρVg

  2. F_b = ρgh

  3. F_b = mg

  4. F_b = Vg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The buoyant force acting on an object submerged in a fluid is given by the equation F_b = ρVg, where F_b is the buoyant force, ρ is the fluid density, V is the volume of the object submerged in the fluid, and g is acceleration due to gravity.

Multiple choice

What is the pressure at the bottom of a container filled with a liquid?

  1. Zero

  2. Equal to atmospheric pressure

  3. Equal to the weight of the liquid

  4. Equal to the weight of the liquid divided by the surface area of the container
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pressure at the bottom of a container filled with a liquid is equal to the weight of the liquid divided by the surface area of the container. This pressure is known as hydrostatic pressure.

Multiple choice

What is the relationship between pressure and height in a liquid?

  1. Pressure is directly proportional to height

  2. Pressure is inversely proportional to height

  3. Pressure is independent of height

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

In a liquid, pressure increases linearly with height. 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 height.

Multiple choice

What is the principle of communicating vessels?

  1. Liquids in communicating vessels will always reach the same level

  2. Liquids in communicating vessels will always reach different levels

  3. Liquids in communicating vessels will reach the same level only if they have the same density

  4. Liquids in communicating vessels will reach the same level only if they have the same temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of communicating vessels states that liquids in communicating vessels will always reach the same level, regardless of their shape or size. This principle is a consequence of Pascal's Law and the fact that liquids seek their own level.

Multiple choice

What is the relationship between the specific gravity of a fluid and its density?

  1. Specific gravity is equal to density

  2. Specific gravity is inversely proportional to density

  3. Specific gravity is independent of density

  4. Specific gravity varies randomly with density
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A Correct answer
Explanation

Specific gravity is defined as the ratio of the density of a substance to the density of water at 4°C. Since the density of water at 4°C is 1000 kg/m^3, the specific gravity of a substance is numerically equal to its density in kg/m^3.

Multiple choice

What is the relationship between the buoyant force acting on an object and the object's density?

  1. Buoyant force is directly proportional to the object's density

  2. Buoyant force is inversely proportional to the object's density

  3. Buoyant force is independent of the object's density

  4. Buoyant force varies randomly with the object's density
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The buoyant force acting on an object is directly proportional to the object's density. This relationship is expressed by the equation F_b = ρVg, where F_b is the buoyant force, ρ is the fluid density, V is the volume of the object submerged in the fluid, and g is acceleration due to gravity.

Multiple choice

What is the primary cause of lift in a fluid?

  1. Pressure difference

  2. Viscosity

  3. Gravity

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

Lift in a fluid is primarily caused by the pressure difference between the upper and lower surfaces of an object moving through the fluid.

Multiple choice

What is the relationship between drag force and the density of the fluid?

  1. Linear

  2. Exponential

  3. Quadratic

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

Drag force is proportional to the density of the fluid.