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 physics free, damped and forced oscillations resonance: examples and uses resonance oscillatory motion

In a resonance column experiment, the first resonance is obtained when the level of the water in tube is $20 cm$ from the open end. Resonance will also be obtained when the water level is at a distance of

  1. $40 cm$ from the open end.
  2. $60 cm$ from the open end.
  3. $80 cm$ from the open end.

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

In a closed pipe : length of the pipe is length of the air column in fundamental.

$\dfrac { \lambda  }{ 4 } =20cm$ 
${ 2 }^{ nd }$ harmonic resonance $=\dfrac { 3\lambda  }{ 4 } =3\times 20=60cm$

$\therefore $  Option (B) is correct.

Multiple choice physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

When a glass filled with water is struck with a stick, ripples are produced in the water. This indicates that

  1. the glass is not vibrating.

  2. the glass may or may not be vibrating.

  3. the glass is vibrating.

  4. none of the above is true.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a glass filled with water is struck with a stick, it vibrates and this vibration creates ripples in the water. These ripples prove that the glass vibrates. Also, a sound is produced due to the vibration of the glass.

Multiple choice physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

A liquid column of height $80cm$ at $0^oC$ balances the same liquid of height $80.4cm$ at $100^oC$. ${\gamma} _{R}$ is

  1. $4 \times {10}^{-5}/^oC$
  2. $3 \times {10}^{-5}/^oC$
  3. $5 \times {10}^{-5}/^oC$
  4. $6 \times {10}^{-5}/^oC$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The coefficient of real expansion gamma_R is given by (h1 - h2) / (h2 * delta_T). Here, (80.4 - 80) / (80 * 100) = 0.4 / 8000 = 0.00005 = 5 * 10^-5 /C.

Multiple choice physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

Real expansion of liquid is :

  1. independent of expansion of the vessel

  2. dependent on expansion of the vessel

  3. independent of nature of the liquid

  4. depends on both nature of the liquid and vessel
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Real expansion is the expansion of the liquid independent of where it is contained and is a property of the liquid. Apparent expansion will depend on  the container.

Multiple choice physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

Coefficient of apparent expansions of a liquid in two different vessels a and b. then the real coefficient of expansions of liquid, if the ratil of volume expansion of vessels is x : y

  1. $\dfrac{ay-bx}{x+y}$
  2. $\dfrac{ay+bx}{x+y}$
  3. $\dfrac{ay-bx}{x-y}$
  4. $\dfrac{ay+bx}{x-y}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Real expansion gamma_R = gamma_apparent + gamma_vessel. Using the given ratios and two vessels, one can derive the expression for real expansion.

Multiple choice biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

1 atm pressure can raise water to a height of more than _____

  1. $10$ feet
  2. $20$ feet
  3. $100$ feet
  4. $32$ feet
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

One atmospheric pressure can raise water to a height of more than $32$ feet. so a pressure of about $13$ atmospheres would be required to raise water at the top of a $416$ feet high tree. The tension developed in the xylem sap of trees that are actively transpiring can be measured only indirectly and has been found to be high as $-77$ bars.

Multiple choice biology absorption by roots - the processes involved root pressure transportation in plants factors affecting the transport of water and minerals in plants

How much pressure would be required to raise water to the top of a $416$ ft. high tree ?

  1. $1$ atm
  2. $13$ atm
  3. $-77$ bars

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

One atmospheric pressure can raise water to a height of more than $32$ feet. So a pressure of about $13$ atmospheres would be required to raise water at the top of a $416$ feet high tree. The tension developed in the xylem sap of trees that are actively transpiring can be measured only indirectly and has been found to be high as $-77$ bars.

Multiple choice evs look, learn and experience brief introduction to atoms of elements elements and atoms introduction of atom

Which of the following changes increases the overall density of the object?

  1. A block of iron is formed into a hollow shape

  2. A submarine fills its ballast tanks with water

  3. A submarine fills its ballast tanks with air

  4. A fish increases the amount of gas in its swim bladder
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When a low-density substance is replaced by high-density substance,the overall density increases.Here air which has low density compared to water is replaced.So,the overall density increases while in removing cases overall density decreases.


Option B is correct.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

Equal masses of three liquid are kept in there identical cylindrical vessels $A, B$ and $C$. There densities are $\rho _{A}, \rho _{B}$ and $\rho _{C}$ with $\rho _{A} < \rho _{B} < \rho _{C}$. The force on the base will be

  1. Maximum in vessel $A$
  2. Maximum in vessel $B$
  3. Maximum in vessel $C$

  4. Same in all the three vessel
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Since masses are same,(weight$=mg$) is same for all three.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

A liquid column of height $80\ cm$ at $0^{\circ}$ balances the same liquid of height $80.4\ cm$ at $100^{\circ}C. \gamma _{R}$ is

  1. $4\times 10^{-5}/ ^{\circ}C$
  2. $3\times 10^{-5}/ ^{\circ}C$
  3. $5\times 10^{-5}/ ^{\circ}C$
  4. $6\times 10^{-5}/ ^{\circ}C$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The coefficient of real expansion gamma_R = (V2 - V1) / (V1 * deltaT). Using the height change as a proxy for volume change: gamma_R = (80.4 - 80) / (80 * 100) = 0.4 / 8000 = 0.00005 = 5e-5 per degree Celsius.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

A block of solid insoluble in water weighs 24 gm in air and 21 gm when completely immersed in water. Its weight when completely immersed in liquid of specific gravity 1.1 is

  1. $20.7 gm$
  2. $27.3 gm$
  3. $24 gm$
  4. $3.3 gm$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The loss in weight in water is 24 - 21 = 3 gm, which is the buoyant force. Since the volume is constant, the buoyant force in another liquid is proportional to its specific gravity. Thus, the loss in the new liquid is 3 * 1.1 = 3.3 gm, and the new weight is 24 - 3.3 = 20.7 gm.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

A $10cm$ long needle can just rest on the surface of water without wetting, its weight is :

  1. $0.014N$
  2. $0.14N$
  3. $1.4N$
  4. $14N$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Surface Tension of Water $(T) = 0.00072 N/cm $


Here, Weight = Surface tension force = $2Tl$

$\Rightarrow Weight = 2 \times 0.00072 \times 10 = 0.014N$

Therefore, A is correct option.