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 botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

According to Dixon and Jolly, cohesive force of water molecules is of the magnitude of ...............

  1. 1 - 10 atm

  2. 10 - 15 atm

  3. 45 - 200 atm

  4. 15 - 45 atm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

One atmospheric pressure of transpiration pull is enough to pull the water unto the height of 20 feet or so; but normally, the transpiration pull that develops runs to about 20-100 atm (it can be as high as 200 atms in case of rapidly transpiring tall trees in tropics), which is enough to pull the water to the height of 400 to 1000 ft and the tallest plant known to mankind is just about 400 ft. 

Multiple choice physics dynamics - explaining motion air resistance fluid friction moving through fluids

If we drop a cup of water on a plate and a cup of oil on another plate, water is seen to spread faster along diameter. This is an example related to:

  1. fluid friction

  2. rolling friction

  3. sliding friction

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

This example relates to fluid friction. Speed of spreading of a volume of liquid depends on the liquid friction.Friction offered by water is less as its density is less than oil.

Multiple choice water potential water potential and pressure plant water relation transport in plants biology

The water potential of imbibants is:

  1. HIghly positive

  2. Zero

  3. Highly negative

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

  • The absorption of water by the solid particles of an adsorbent without forming a solution is called Imbibition.
  • Imbibants have very high negative water potential. It is called the matric potential. Water has (the highest) maximum water potential (maximum being zero).

So, the correct option is 'Highly negative'.

Multiple choice

Water has maximum density at..

  1. 32 0C

  2. 4 0C

  3. 100 0C

  4. 00C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water exhibits the anomalous property of having its maximum density at 4 degrees Celsius. Below this temperature, it begins to expand as it forms a crystalline structure.

Multiple choice physics force and newton's laws of motion concept of inertia galileo's law and inertia mass and inertia

A water tanker filled up to $\dfrac {2}{3}$rd of its height is moving with a uniform speed. On sudden application of the brake, the water in the tank would

  1. move backward

  2. move forward

  3. be unaffected

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

Basically, the law of motion is that an object at rest stays at rest and an object continues in motion until an external force acts on it.
Inertia is the resistance of any physical object to any change in its state of motion, including changes to its speed and direction. It is the tendency of objects to keep moving in a straight line at constant velocity.


So, on sudden application of brakes on the water tank, the water tank decelerates or may even stop but the water in the tank still has a tendency to move forward due to inertia. Hence the water in the tank would move forward.
A water tanker filled up to two-thirds of its height moving with a uniform speed, on sudden application of the brake, the water in the tank would move forward.

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. $100$ cm from the open end
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation
For $1^{st}$ resonance $(1/4)\lambda =L$
$\Rightarrow \lambda =4L$ ..(i)
For $2$nd resonance
$3\left(\dfrac{\lambda}{4}\right)=L _2\Rightarrow \lambda =\dfrac{4L _2}{3}$ .(ii)
By using (i) and (ii)
$\dfrac{4L _2}{3}=4L _1$
$\Rightarrow L _2=3L _1=3(20)=60$cm
Similarly, $L _3=5L _1=100$ cm
Hence (B) and (D) are correct.
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.