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 maths how big? how heavy? measuring volume volume of solids volume of cube and cuboid

If $210m^$ of sand be thrown into a tank $12$m long and $5$m wide, find how much the water will rise?

  1. $3.5$m
  2. $4$m
  3. $7$m

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

Assuming '210m³' of sand, volume = 210 m³. Tank base area = 12 × 5 = 60 m². Rise in water level = 210/60 = 3.5 m. This matches option A. Options B and C are incorrect calculations.

Multiple choice fluid dynamics option b: engineering physics physics

Two identical lead shots are dropped at the same time in two glass jars containing water and glycerine. The lead shot dropped in glycerine descends slowly because:

  1. Viscous force is more in water than in glycerine

  2. Viscous force is more in glycerine than in water

  3. Surface tension is more in water

  4. Surface tension is more in glycerine
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glycerine viscosity is 950 cP and water viscosity is 0.89 cP. We can see that glycerine has high viscosity. High viscous force of glycerine increases the time of drop of lead shot than in water.

Multiple choice fluid dynamics option b: engineering physics physics

When stirring of a liquid is stopped, the liquid comes to rest due to:

  1. surface tension

  2. gravity

  3. viscosity

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

When stirring of a liquid is stopped, the liquid comes to rest due to viscosity of liquid. While stirring fluid at the axis moves faster in circular path whereas the fluid in contact with the walls does not move. So, the viscous drag force acting between the fluid layers tries to restrict the relative motion of them. So, by viscous drag force liquid comes to rest. 

Multiple choice fluid dynamics option b: engineering physics physics

When an object is dropped into a fluid, the extent of splash, due to buoyant force of fluid, depends on:

  1. sliding friction

  2. rolling friction

  3. fluid friction

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

The splash, due to buoyant force of a fluid depends on fluid friction.

Multiple choice fluid dynamics option b: engineering physics physics

Two spheres $A$ and $B$ fall through the same viscous fluid. $A$ and $B$ have the same density and $B$ has the larger radius.
Then,

  1. A has the larger terminal velocity

  2. A and B have the same terminal velocity

  3. B has the larger terminal velocity

  4. Insufficient information is given to reach a conclusion.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Two spheres $A$ and $B$ fall through the same viscous fluid $A$ and $B$ have  the same density and $B$ has the larger radius the $B$ has the larger terminal velocity.

$\therefore $ Option $C$ is correct.

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

0.5 M sucrose develops a pressure of 15 bars  in an osmometer. Which of the following statement is wrong for such a solution ______________.

  1. That its osmotic potential is-15 bars

  2. That its water potential is-15 bars

  3. That its pressure potential is-15 bars

  4. That its osmotic potential is+15 bars
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pressure potential is usually positive.

So the incorrect option is C.

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.