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 botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

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
Cohesive force is called as the tensile strength of water. It is the force which acts between the water molecules. The cohesive strength of 47-207 atm. in xylem sap is sufficient to meet the stress of transpiration pull so that water column does not break.
Thus, the correct answer is option (C). 
Multiple choice chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

Two students are working on an AP Chemistry lab. Their assignment is to determine experimentally the density of a nonvolatile organic liquid, limestone. The accepted value for the density of limestone is $0.8422\ g/mL$. Each student conducts three separate density determinations, then calculates a mean (average) value for the density and the standard deviation for their three trials.

Student A Student B
Density #$1$ $0.8421 g/mL$ $0.8408 g/mL$
Density #$2$ $0.8514 g/mL$ $0.8502 g/mL$
Density #$3$ $0.8355 g/mL$ $0.8332 g/mL$
Mean Density $0.8430 g/mL$ $0.8414 g/mL$
Standard Deviation $0.0080$ $0.0085$

The results and calculations for each students are shown in the table below.
Of the four descriptions given below, which BEST interprets the accuracy and precision of Student A and Student B?

  1. Student A and Student B are equally precise, but Student B has more accurate results.

  2. Student A and Student B are equally accurate, but Student B has more precise results.

  3. Student A and Student B have equal accuracy and equal precision.

  4. Student A has more accurate and more precise results than Student B.
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice biology option c: ecology and conservation hotspots and methods of conservation biodiversity: conservation conservation of biodiversity

What will be percentage of water absorbed?

  1. $\displaystyle\frac {U - V}{100} X 50$
  2. $\displaystyle\frac {V - U}{50} X 100$
  3. $\displaystyle\frac {U - V}{50} X100$
  4. $\displaystyle\frac {V - U}{100} X50$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

U - V ? 50 * 100 is the percentage of water absorbed where, 

U is the initial volume of water and V is the final volume of water. 
So, option C is the correct answer.

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

Assertion(A): Real expansion of liquid does not depend up on material of container.

Reason (R): Liquids have no definite shape. They acquire the mouth of the containers in which they are taken.

  1. Both A and R are true and R is the correct explanation of A

  2. Both A & R are true but R is not the correct explanation of A.

  3. A is true but R is false

  4. A is false but R istrue
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Real expansion would not be affected by the size and shape of container. Because of liquid has no any definate shape.
Both assertion and reason are true and reason is correct explanation.

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

(1): when a liquid with a coefficient of $\gamma $ is heated in a vessel of a coefficient of linear expansion $\frac{\gamma }{3}$, the level of liquid in the vessel remains unchanged.

 (2):$\gamma _{a}=\gamma _{r}-\gamma _{g}=\gamma _{r}-3\alpha =0$

  1. Both 1 and 2 are true and 2 is the correct explanation of 1

  2. Both 1 & 2 are true but 2 is not the correct explanation of 1.

  3. 1 is true but 2 is false

  4. 1 is false but 2 is true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Coefficient of volume expansion is thrice the coefficient of linear expansion. Hence the coefficient of expansion of both liquid and vessel is same. Hence they expand equally with rise in temperature. Therefore no rise in the level of liquid in vessel is observed.

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

The co-efficient of apparent expansion of a liquid in a vessel A is $18\times 10^{-4}/^oC$ and in vessel B is $21\times 10^{-4}/^oC$. The difference in the coefficients of linear expansions of A and B is :

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

${\gamma} _r={\gamma} _a +{\gamma} _g={\gamma} _a +3{\alpha} _g$
${\gamma} _r={\gamma} _{a1} +3{\alpha} _1={\gamma} _{a2} +3{\alpha} _2$ for both vessels A and B
$ \therefore 18 \times 10^{-4} + 3{\alpha} _1= 21 \times 10^{-4}+ 3{\alpha} _2$
$ \therefore3( {\alpha} _1- {\alpha} _2) = 3 \times 10^{-4}$
$ \therefore {\alpha} _1- {\alpha} _2 = 1 \times 10^{-4}$/ $^{0}$C

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

A specific gravity bottle is filled up to the brim with mercury of 400g, at $0^{0}$C. When heated to $90^{0}$C, the mass of the mercury that overflows from the specific gravity bottle is : (Coefficient of apparent expansion of mercury in glass is $\frac{1}{6500}/^{0}C$

  1. 5.46g

  2. 6.54g

  3. 10.92g

  4. 13.08 g
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Coefficient of apparent expansion is the ratio of liquid spilled out to the liquid left in the bottle per unit degree change in temperature.

$\gamma _{a}=\dfrac{mass   spilled }{mass   left \times \Delta \theta  }$
Let the mass spilled be x.
$\gamma _{a}=\dfrac{x}{(400-x)(90)}$
$\implies x=5.46g$

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

The coefficient of apparent expansion of a liquid when determined using two different vessels A and B are $\gamma _{1}$ and $\gamma _{2}$ respectively. If the coefficient of linear expansion of the vessel A is $\alpha $, the coefficient of linear expansion of the vessel B is

  1. $\dfrac{\alpha \gamma _{1}\gamma _{2}}{\gamma _{1}+\gamma _{2}}$
  2. $\dfrac{\gamma _{1}-\gamma _{2}}{2\alpha }$
  3. $\dfrac{\gamma _{1}-\gamma _{2}+\alpha }{3}$
  4. $\dfrac{\gamma _{1}-\gamma _{2}}{3}+\alpha $
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\gamma _r = \gamma _l + \gamma _g=\gamma _r + 3\alpha _g$
Given,
$\gamma _r = \gamma _1 + 3\alpha _1$ ....(1)
$\gamma _r = \gamma _2 + 3\alpha _2$ ....(2)
Equating (1) and (2),
$\gamma _1 + 3\alpha _1= \gamma _2 + 3\alpha _2$
$ \therefore \alpha _2 =\frac{ \gamma _1 - \gamma _2}{3} + \alpha _1$

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

The coefficient of apparent expansion of mercury in a glass vessel is $153 \times 10^{-6}/^{\circ}C$ and in a steel vessel is $144 \times 10^{-6} / ^{\circ}C$. If $\alpha$ for steel is then, that of glass is $12 \times 10^{-6} / ^{\circ}C$.then that of glass is

  1. $ 9\times 10^{-6} / ^{\circ}C$.
  2. $ 6\times 10^{-6} / ^{\circ}C$.
  3. $36 \times 10^{-6} / ^{\circ}C$.
  4. $27 \times 10^{-6} / ^{\circ}C$.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$We\quad know\quad that\quad γ _{ real }=γ _{ apparent }+γ _{ vessel }\ So,(γ _{ app }+γ _{ vessel }) _{ glass }=(γ _{ app }+γ _{ vessel }) _{ steel }\ (∴γ _{ real }\quad is\quad same\quad in\quad both\quad cases)\quad or\quad \ 153×{ 10 }^{ -6 }+(γ _{ vessel }) _{ glass }=144×{ 10 }^{ -6 }+(γ\ _ { vessel} )\ _ { steel} \ Further(\gamma \ _ { vessel })\ _ { steel} =3α=3×(12×{ 10 }^{ -6 })=36×{ 10 }^{ -6 }/∘C\ ∴153×10−6+(γ _{ vessel }) _{ glass }=144×{ 10 }^{ -6 }+36×{ 10 }^{ -6 }\ Solving\quad we\quad get\quad (γ\ _ { vessel} )\ _ { glass} =27×10−6/∘C(γ\ _ { vessel} )\ _ { glass} \quad or\\quad α=\frac{ γ _{ glass } }{ 3 }=9×10−6/∘C$

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

The principle of fluid pressure that is used in hydraulic brakes or lifts is that.

  1. pressure is the same at all levels in a fluid.

  2. increases of pressure are transmitted equally to all parts of a fluid.

  3. the pressure at a point in a fluid is due to the weight of the fluid above it.

  4. increases of pressure can only be transmitted through fluids.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B.
Hydraulics is the use of a liquid under pressure to transfer force or motion, or to increase an applied force. The pressure on a liquid is called HYDRAULIC PRESSURE. And the brakes which are operated by means of hydraulic pressure are called HYDRAULIC BRAKES. These brakes are based on the principle of Pascals law. 
The Pascal law states that 'The pressure exerted anywhere in a mass of confined liquid is transmitted undiminished in all directions throughout the liquid'.

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

The center of pressure of surface subjected to fluid pressure is the point

  1. on the surface at which resultant pressure acts

  2. on the surface at which gravitational force acts

  3. equal to volume of liquid displaced

  4. none
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The center of pressure of surface subjected to fluid pressure is the point on the surface at which gravitational force acts

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

An enclosed fluid under pressure exerts that pressure throughout its volume and against any surface containing it. Is the statement true or false

  1. True

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

It is true that an enclosed fluid under pressure exerts that pressure throughout its volume and against any surface containing it.

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

When two cylinder with different size like larger and smaller are kept together then though the pressure is same in both, still the force required is more for larger cylinder. Due to increase in which property?

  1. Area

  2. height

  3. Weight

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

Force required        $F = PA$    

$\implies$    $F\propto A$                          $(\because P = constant)$
Thus option A is correct.

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

If the system is not in free fall, which of the following statements is true about hydrostatic pressure?

  1. In a liquid, point at different depth can never be at the same pressure.

  2. In a liquid, point at different depth may be at the same pressure.

  3. In different liquids, points at different depths can be at the same pressure.

  4. In different liquids, points at the same depths can never be at the same pressure.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

pressure for same liquid is $\rho gh$

at same depth  pressure is same   as for specific liquid density is constant and depth is same 
 for different liquid 
pressure at different depth can be same as  $\rho h$ can be constant for different liquid 
but for different liquid pressure at same depth cannot be same as density is different and depth is same so pressure cannot be same

Multiple choice physics pressure in fluids and atmospheric pressure hydraulic equipment applications of pascals law examples of hydraulic press

A U-tube is partially filled with water. Oil which does not mix with water is next poured into one side, until water rises by $25\;cm$ on the other side. If the density of oil is $0.8\;g/cc$, the oil level will stand higher than the water level by

  1. $6.25\;cm$
  2. $12.50\;cm$
  3. $18.75\;cm$
  4. $25.00\;cm$
Reveal answer Fill a bubble to check yourself
B Correct answer