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All questions of Fluid Mechanics for Mechanical Engineering Exam
A mercury-water manometer has a gauge difference of 500 mm(difference in elevation of menisci). What will be the difference in pressure? - a)0.5 m
- b)6.3 m
- c)6.8 m
- d)7.3m
Correct answer is option 'B'. Can you explain this answer?
A mercury-water manometer has a gauge difference of 500 mm(difference in elevation of menisci). What will be the difference in pressure?
a)
0.5 m
b)
6.3 m
c)
6.8 m
d)
7.3m
|
Sanvi Kapoor answered |
Ans. (b)
m of light fluid or h = 0.5
= 6.3m of water.
Consider the following statements:
1. Gases are considered incompressible when Mach number isless than 0.2
2. A Newtonian fluid is incompressible and non-viscous
3. An ideal fluid has negligible surface tension
Which of these statements is /are correct?- a)2 and 3
- b)2 alone
- c)1 alone
- d)1 and 3
Correct answer is option 'D'. Can you explain this answer?
Consider the following statements:
1. Gases are considered incompressible when Mach number isless than 0.2
2. A Newtonian fluid is incompressible and non-viscous
3. An ideal fluid has negligible surface tension
Which of these statements is /are correct?
1. Gases are considered incompressible when Mach number isless than 0.2
2. A Newtonian fluid is incompressible and non-viscous
3. An ideal fluid has negligible surface tension
Which of these statements is /are correct?
a)
2 and 3
b)
2 alone
c)
1 alone
d)
1 and 3
|
Zoya Sharma answered |
Ans. (d)
A tank containing water has two orifices of the same size at depths of 40 cm and 90 cm below the free surface of water. The ratio of discharges through these orifices is: - a)1 : 1
- b)2: 3
- c)4: 9
- d)16: 81
Correct answer is option 'B'. Can you explain this answer?
A tank containing water has two orifices of the same size at depths of 40 cm and 90 cm below the free surface of water. The ratio of discharges through these orifices is:
a)
1 : 1
b)
2: 3
c)
4: 9
d)
16: 81
|
Rahul Chatterjee answered |
For the same size of the orifices ,the ratio of discharges will be proportional to jet velocities which in turn will be proportional to their square root of heads of water .So Q1/Q2 = √40/90 = 2/3.
For floating bodies, how is the metacentric radius defined? - a)The distance between centre of gravity and the metacentre.
- b)Second moment of area of plane of flotation about centroidal axisperpendicular to plane of rotation/immersed volume.
- c)The distance between centre of gravity and the centre of buoyancy.
- d)Moment of inertia of the body about its axis of rotation/immersedvolume.
Correct answer is option 'A'. Can you explain this answer?
For floating bodies, how is the metacentric radius defined?
a)
The distance between centre of gravity and the metacentre.
b)
Second moment of area of plane of flotation about centroidal axisperpendicular to plane of rotation/immersed volume.
c)
The distance between centre of gravity and the centre of buoyancy.
d)
Moment of inertia of the body about its axis of rotation/immersedvolume.
|
Divyansh Goyal answered |
Ans. (a) Metacentric Radius or Metacentric Height is the distance between Centre of Gravity and the Metacentre.
Assertion (A): In a fluid, the rate of deformation is far more important than the total deformation it self.
Reason (R): A fluid continues to deform so long as the external forces are applied.- a)Both A and R are individually true and R is the correct explanation ofA.
- b)Both A and R are individually true but R is not the correct explanationof A.
- c)A is true but R is false.
- d)A is false but R is true.
Correct answer is option 'A'. Can you explain this answer?
Assertion (A): In a fluid, the rate of deformation is far more important than the total deformation it self.
Reason (R): A fluid continues to deform so long as the external forces are applied.
Reason (R): A fluid continues to deform so long as the external forces are applied.
a)
Both A and R are individually true and R is the correct explanation ofA.
b)
Both A and R are individually true but R is not the correct explanationof A.
c)
A is true but R is false.
d)
A is false but R is true.
|
Gauri Sen answered |
Ans. (a) This question is copied from Characteristics of fluid
1. It has no definite shape of its own, but conforms to the shape of the containing vessel.
2. Even a small amount of shear force exerted on a fluid will cause it to undergo a deformation which continues as long as
the force continues to be applied.
3. It is interesting to note that a solid suffers strain when subjected to shear forces whereas a fluid suffers Rate of Strain i.e. it flows under similar circumstances.
1. It has no definite shape of its own, but conforms to the shape of the containing vessel.
2. Even a small amount of shear force exerted on a fluid will cause it to undergo a deformation which continues as long as
the force continues to be applied.
3. It is interesting to note that a solid suffers strain when subjected to shear forces whereas a fluid suffers Rate of Strain i.e. it flows under similar circumstances.
The gross head available to a hydraulic power plant is 100 m. The utilized head in the runner of the hydraulic turbine is 72 m. If the'hydraulic efficiency of the turbine is 90%, the pipe friction head is estimated to be: - a)20 m
- b)18 m
- c)16.2 m
- d)1.8 m
Correct answer is option 'A'. Can you explain this answer?
The gross head available to a hydraulic power plant is 100 m. The utilized head in the runner of the hydraulic turbine is 72 m. If the'hydraulic efficiency of the turbine is 90%, the pipe friction head is estimated to be:
a)
20 m
b)
18 m
c)
16.2 m
d)
1.8 m
|
Palak Mehta answered |
Ans. (a)
Consider the following types of water turbines:
1. Bulb
2. Francis
3. Kaplan
4. Pelton
The correct sequence of order in which the operating head decreases while developing the same power is- a)4 – 2 – 3 – 1
- b)3 – 4 – 1 – 2
- c)2 – 1 – 4 – 3
- d)1 – 3 – 2 – 4
Correct answer is option 'A'. Can you explain this answer?
Consider the following types of water turbines:
1. Bulb
2. Francis
3. Kaplan
4. Pelton
The correct sequence of order in which the operating head decreases while developing the same power is
1. Bulb
2. Francis
3. Kaplan
4. Pelton
The correct sequence of order in which the operating head decreases while developing the same power is
a)
4 – 2 – 3 – 1
b)
3 – 4 – 1 – 2
c)
2 – 1 – 4 – 3
d)
1 – 3 – 2 – 4
|
Jyoti Deshpande answered |
Ans. (a)
Consider the following statements:
1. Streak line indicates instantaneous position of particles offluid passing through a point.
2. Streamlines are paths traced by a fluid particle with constantvelocity.
3. Fluid particles cannot cross streamlines irrespective of thetype of flow.
4. Streamlines converge as the fluid is accelerated, and diverge when retarded.
Which of these statements are correct?- a)1 and 4
- b)1, 3 and 4
- c)1, 2 and 4
- d)2 and 3
Correct answer is option 'B'. Can you explain this answer?
Consider the following statements:
1. Streak line indicates instantaneous position of particles offluid passing through a point.
2. Streamlines are paths traced by a fluid particle with constantvelocity.
3. Fluid particles cannot cross streamlines irrespective of thetype of flow.
4. Streamlines converge as the fluid is accelerated, and diverge when retarded.
Which of these statements are correct?
1. Streak line indicates instantaneous position of particles offluid passing through a point.
2. Streamlines are paths traced by a fluid particle with constantvelocity.
3. Fluid particles cannot cross streamlines irrespective of thetype of flow.
4. Streamlines converge as the fluid is accelerated, and diverge when retarded.
Which of these statements are correct?
a)
1 and 4
b)
1, 3 and 4
c)
1, 2 and 4
d)
2 and 3
|
Lekshmi Das answered |
Statement Analysis:
Let's analyze each statement one by one:
Statement 1: Streak line indicates instantaneous position of particles of fluid passing through a point.
A streak line represents the path traced by a fluid particle over a certain period of time. It shows the history of the fluid particle's movement. Therefore, statement 1 is incorrect.
Statement 2: Streamlines are paths traced by a fluid particle with constant velocity.
Streamlines represent the instantaneous direction of fluid flow at each point in the fluid. Fluid particles along a streamline move parallel to each other and maintain a constant velocity. Therefore, statement 2 is correct.
Statement 3: Fluid particles cannot cross streamlines irrespective of the type of flow.
Streamlines are imaginary lines that do not have any physical existence. They represent the direction of fluid flow at each point. Fluid particles can cross each other's path, but they cannot cross streamlines. Therefore, statement 3 is correct.
Statement 4: Streamlines converge as the fluid is accelerated, and diverge when retarded.
Streamlines converge when the fluid is accelerated because the fluid particles are brought closer together. On the other hand, streamlines diverge when the fluid is retarded because the fluid particles move away from each other. Therefore, statement 4 is correct.
Correct Statements:
Based on the analysis above, the correct statements are:
- Statement 2: Streamlines are paths traced by a fluid particle with constant velocity.
- Statement 3: Fluid particles cannot cross streamlines irrespective of the type of flow.
- Statement 4: Streamlines converge as the fluid is accelerated, and diverge when retarded.
Therefore, the correct option is option B, which includes statements 1, 3, and 4.
Let's analyze each statement one by one:
Statement 1: Streak line indicates instantaneous position of particles of fluid passing through a point.
A streak line represents the path traced by a fluid particle over a certain period of time. It shows the history of the fluid particle's movement. Therefore, statement 1 is incorrect.
Statement 2: Streamlines are paths traced by a fluid particle with constant velocity.
Streamlines represent the instantaneous direction of fluid flow at each point in the fluid. Fluid particles along a streamline move parallel to each other and maintain a constant velocity. Therefore, statement 2 is correct.
Statement 3: Fluid particles cannot cross streamlines irrespective of the type of flow.
Streamlines are imaginary lines that do not have any physical existence. They represent the direction of fluid flow at each point. Fluid particles can cross each other's path, but they cannot cross streamlines. Therefore, statement 3 is correct.
Statement 4: Streamlines converge as the fluid is accelerated, and diverge when retarded.
Streamlines converge when the fluid is accelerated because the fluid particles are brought closer together. On the other hand, streamlines diverge when the fluid is retarded because the fluid particles move away from each other. Therefore, statement 4 is correct.
Correct Statements:
Based on the analysis above, the correct statements are:
- Statement 2: Streamlines are paths traced by a fluid particle with constant velocity.
- Statement 3: Fluid particles cannot cross streamlines irrespective of the type of flow.
- Statement 4: Streamlines converge as the fluid is accelerated, and diverge when retarded.
Therefore, the correct option is option B, which includes statements 1, 3, and 4.
How is the best hydraulic channel cross-section defined? - a)The section with minimum roughness coefficient.
- b)The section that has a maximum area of a given flow.
- c)The section that has a minimum wetted perimeter
- d)The section that has a maximum wetted area.
Correct answer is option 'C'. Can you explain this answer?
How is the best hydraulic channel cross-section defined?
a)
The section with minimum roughness coefficient.
b)
The section that has a maximum area of a given flow.
c)
The section that has a minimum wetted perimeter
d)
The section that has a maximum wetted area.
|
Mrinalini Sharma answered |
Ans. (c)
The equation of the velocity distribution over a plate is given byu = 2y – y2 where u is the velocity in m/s at a point y meter from theplate measured perpendicularly. Assuming μ = 8.60 poise, the shearstress at a point 15 cm from the boundary is: - a)1.72 N/m2
- b)1.46 N/m2
- c)14.62 N/m2
- d)17.20 N/m2
Correct answer is option 'B'. Can you explain this answer?
The equation of the velocity distribution over a plate is given byu = 2y – y2 where u is the velocity in m/s at a point y meter from theplate measured perpendicularly. Assuming μ = 8.60 poise, the shearstress at a point 15 cm from the boundary is:
a)
1.72 N/m2
b)
1.46 N/m2
c)
14.62 N/m2
d)
17.20 N/m2
|
Hiral Jain answered |
Ans. (b)
A metal plate 1.25 m × 1.25 m × 6 mm thick and weighting 90 N is placed midway in the 24 mm gap between the two vertical plane surfaces. The Gap is filled with an oil of specific gravity 0.85 and dynamic viscosity 3.0N.s/m2. Determine the force required to lift the plate with a constant velocity of 0.15 m/s.Correct answer is '168.08N'. Can you explain this answer?
A metal plate 1.25 m × 1.25 m × 6 mm thick and weighting 90 N is placed midway in the 24 mm gap between the two vertical plane surfaces. The Gap is filled with an oil of specific gravity 0.85 and dynamic viscosity 3.0N.s/m2. Determine the force required to lift the plate with a constant velocity of 0.15 m/s.
|
|
Ayush Chawla answered |
Ans. 168.08N
The gross head on a turbine is 300 m. The length of penstock supplying water from reservoir to the turbine is 400 m. The diameter of the penstock is 1 m and velocity of water through penstock is 5 m/s. If coefficient of friction is 0.0098, the net head on the turbine would benearly - a)310 m
- b)295 m
- c)200 m
- d)150 m
Correct answer is option 'B'. Can you explain this answer?
The gross head on a turbine is 300 m. The length of penstock supplying water from reservoir to the turbine is 400 m. The diameter of the penstock is 1 m and velocity of water through penstock is 5 m/s. If coefficient of friction is 0.0098, the net head on the turbine would benearly
a)
310 m
b)
295 m
c)
200 m
d)
150 m
|
Saranya Saha answered |
Ans. (b)
The correct sequence of the centrifugal pump components through which the fluid flows is: - a)Impeller, Suction pipe, Foot valve and strainer, Delivery pipe
- b)Foot valve and strainer, Suction pipe, Impeller, Delivery pipe
- c)Impeller, Suction pipe, Delivery pipe, Foot valve strainer
- d)Suction pipe, Delivery pipe, Impeller, Foot valve and strainer
Correct answer is option 'B'. Can you explain this answer?
The correct sequence of the centrifugal pump components through which the fluid flows is:
a)
Impeller, Suction pipe, Foot valve and strainer, Delivery pipe
b)
Foot valve and strainer, Suction pipe, Impeller, Delivery pipe
c)
Impeller, Suction pipe, Delivery pipe, Foot valve strainer
d)
Suction pipe, Delivery pipe, Impeller, Foot valve and strainer
|
|
Gaurav Kapoor answered |
Ans. (b)
A journal bearing has a journal diameter of 80 mm and a bush diameter of 81 mm. The bearing length is 25 mm, and the rotational speed of the journal is 1500 rpm. The viscosity of the lubricant is 0.4 Pa-s. What is the power loss due to friction in the bearing?- a)4.93 W
- b)75 W
- c)100 W
- d)150 W
Correct answer is option 'A'. Can you explain this answer?
A journal bearing has a journal diameter of 80 mm and a bush diameter of 81 mm. The bearing length is 25 mm, and the rotational speed of the journal is 1500 rpm. The viscosity of the lubricant is 0.4 Pa-s. What is the power loss due to friction in the bearing?
a)
4.93 W
b)
75 W
c)
100 W
d)
150 W
|
Gate Funda answered |
- Journal diameter: 80 mm; Bush diameter: 81 mm; Clearance = 1 mm.
- Bearing length: 25 mm; Rotational speed: 1500 rpm.
- Viscosity = 0.4 Pa-s.
- Frictional torque, T = (2π × Speed × Viscosity × Length × Clearance) / Diameter.
- Convert speed: 1500 rpm = 1500 × (2π / 60) rad/s = 157.08 rad/s.
- Torque, T = (2π × 157.08 × 0.4 × 0.025 × 0.001) / 0.08 = 0.0314 Nm.
- Power loss = Torque × Angular speed = 0.0314 × 157.08 = 4.93 W.
- However, no option matches the calculated 4.93 W.
A compound pipe is required to be replaced by a new pipe. The two pipes are said to be equivalent, if- a)Length of both the pipes is same
- b) Diameter of both the pipes is same
- c)Loss of head and discharge of both the pipes is same
- d) Loss of head and velocity of flow in both the pipes is same
Correct answer is option 'C'. Can you explain this answer?
A compound pipe is required to be replaced by a new pipe. The two pipes are said to be equivalent, if
a)
Length of both the pipes is same
b)
Diameter of both the pipes is same
c)
Loss of head and discharge of both the pipes is same
d)
Loss of head and velocity of flow in both the pipes is same
|
Vaibhav Khanna answered |
Equivalent Pipes in Fluid Mechanics
Introduction:
In fluid mechanics, the concept of equivalent pipes is used to compare two pipes based on their hydraulic characteristics. The two pipes are said to be equivalent when they have the same head loss and discharge.
Factors to consider:
To determine the equivalence of two pipes, several factors are considered. These include:
- Length of the pipes
- Diameter of the pipes
- Loss of head in the pipes
- Discharge of the pipes
- Velocity of flow in the pipes
Criteria for equivalence:
Based on the above factors, the following criteria are used to determine the equivalence of two pipes:
- Length of the pipes: If the lengths of the two pipes are the same, they are considered equivalent.
- Diameter of the pipes: If the diameters of the two pipes are the same, they are considered equivalent.
- Loss of head and discharge of the pipes: If the two pipes have the same head loss and discharge, they are considered equivalent.
- Loss of head and velocity of flow in the pipes: If the two pipes have the same head loss and velocity of flow, they are considered equivalent.
Conclusion:
In conclusion, the equivalence of two pipes in fluid mechanics is determined based on several factors, including length, diameter, head loss, discharge, and velocity of flow. The two pipes are considered equivalent if they have the same head loss and discharge or the same head loss and velocity of flow.
Introduction:
In fluid mechanics, the concept of equivalent pipes is used to compare two pipes based on their hydraulic characteristics. The two pipes are said to be equivalent when they have the same head loss and discharge.
Factors to consider:
To determine the equivalence of two pipes, several factors are considered. These include:
- Length of the pipes
- Diameter of the pipes
- Loss of head in the pipes
- Discharge of the pipes
- Velocity of flow in the pipes
Criteria for equivalence:
Based on the above factors, the following criteria are used to determine the equivalence of two pipes:
- Length of the pipes: If the lengths of the two pipes are the same, they are considered equivalent.
- Diameter of the pipes: If the diameters of the two pipes are the same, they are considered equivalent.
- Loss of head and discharge of the pipes: If the two pipes have the same head loss and discharge, they are considered equivalent.
- Loss of head and velocity of flow in the pipes: If the two pipes have the same head loss and velocity of flow, they are considered equivalent.
Conclusion:
In conclusion, the equivalence of two pipes in fluid mechanics is determined based on several factors, including length, diameter, head loss, discharge, and velocity of flow. The two pipes are considered equivalent if they have the same head loss and discharge or the same head loss and velocity of flow.
Assertion (A): In general, viscosity in liquids increases and ingases it decreases with rise in temperature. Reason (R): Viscosity is caused by inter molecular forces of cohesion and due to transfer of molecular momentum between fluid layers; of which in liquids the former and in gases the later contribute the major part towards viscosity.- a)Both A and R are individually true and R is the correct explanation ofA
- b)Both Aand Rare individually true but Ris not the correct explanationof A
- c)A is true but R is false
- d)A is false but R is true
Correct answer is option 'D'. Can you explain this answer?
Assertion (A): In general, viscosity in liquids increases and ingases it decreases with rise in temperature. Reason (R): Viscosity is caused by inter molecular forces of cohesion and due to transfer of molecular momentum between fluid layers; of which in liquids the former and in gases the later contribute the major part towards viscosity.
a)
Both A and R are individually true and R is the correct explanation ofA
b)
Both Aand Rare individually true but Ris not the correct explanationof A
c)
A is true but R is false
d)
A is false but R is true
|
|
Deepika Choudhary answered |
Viscosity is higher in liquids than gases as the temperature increases. It will certainly change its state to gas and so the viscosity will decrease. The reason is true it is due to the friction between fluid layers.
Which one of the following statements is true to two dimensional flow of ideal fluids? - a)Potential function exists if stream function exists.
- b)Stream function may or may not exist.
- c)Both potential function and stream function must exist for every flow.
- d)Stream function will exist but potential function may or may not exist.
Correct answer is option 'D'. Can you explain this answer?
Which one of the following statements is true to two dimensional flow of ideal fluids?
a)
Potential function exists if stream function exists.
b)
Stream function may or may not exist.
c)
Both potential function and stream function must exist for every flow.
d)
Stream function will exist but potential function may or may not exist.
|
|
Rahul Chatterjee answered |
For a possible case of fluid flow Stream function will exist, but potential function will exist only for irrotational flow. In this case flow may be rotational or irrotational.
Can you explain the answer of this question below:Which one of the following statements is correct? ]A steady flow of diverging straight stream lines
- A:
Is a uniform flow with local acceleration
- B:
Has convective normal acceleration
- C:
Has convective tangential acceleration
- D:
Has both convective normal and tangential accelerations
The answer is c.
Which one of the following statements is correct? ]A steady flow of diverging straight stream lines
Is a uniform flow with local acceleration
Has convective normal acceleration
Has convective tangential acceleration
Has both convective normal and tangential accelerations
|
Devanshi Iyer answered |
Ans. (c)
For flow over a flat plate the hydrodynamic boundary layer thicknessis 0.5 mm. The dynamic viscosity is 25 × 10-6 Pa s, specific heat is 2.0kJ/(kgK) and thermal conductivity is 0.05 W/(m–K). The thermal boundary layer thickness would be: - a)0.1 mm
- b)0.5 mm
- c)1 mm
- d)2 mm
Correct answer is option 'B'. Can you explain this answer?
For flow over a flat plate the hydrodynamic boundary layer thicknessis 0.5 mm. The dynamic viscosity is 25 × 10-6 Pa s, specific heat is 2.0kJ/(kgK) and thermal conductivity is 0.05 W/(m–K). The thermal boundary layer thickness would be:
a)
0.1 mm
b)
0.5 mm
c)
1 mm
d)
2 mm
|
|
Ravi Singh answered |
Ans. (b)
A cylindrical piece of cork weighting 'W' floats with its axis in horizontal position in a liquid of relative density 4. By anchoring the bottom, the cork piece is made to float at neutral equilibrium position with its axis vertical. The vertically downward force exerted by anchoring would be: - a)0.5 W
- b)W
- c)2W
- d)3 W
Correct answer is option 'D'. Can you explain this answer?
A cylindrical piece of cork weighting 'W' floats with its axis in horizontal position in a liquid of relative density 4. By anchoring the bottom, the cork piece is made to float at neutral equilibrium position with its axis vertical. The vertically downward force exerted by anchoring would be:
a)
0.5 W
b)
W
c)
2W
d)
3 W
|
|
Divyansh Goyal answered |
Ans. (d) Due to own weight of cylinder, it will float upto 1/4th of its height in liquid of relative density of 4. To make it float in neutral equilibrium, centre of gravity and centre of buoyancy must coincide, i.e. cylinder upto full height must get immersed.
For free floating: Weight (W) = Buoyancy force (i.e. weight of liquid equal to 1/4th volume cork) The vertically downward force exerted by anchoring would be weight of
liquid equal to 3/4th volume cork = 3W.
For free floating: Weight (W) = Buoyancy force (i.e. weight of liquid equal to 1/4th volume cork) The vertically downward force exerted by anchoring would be weight of
liquid equal to 3/4th volume cork = 3W.
Which of the following advantages is/are possessed by a Kaplan turbine over a Francis turbine?
1. Low frictional losses.
2. Part load efficiency is considerably high
3. More compact and smaller in size.
Select the correct answer using the codes given below- a)Only 1
- b)Only 1 and 2
- c)Only 2 and 3
- d)1, 2 and 3
Correct answer is option 'D'. Can you explain this answer?
Which of the following advantages is/are possessed by a Kaplan turbine over a Francis turbine?
1. Low frictional losses.
2. Part load efficiency is considerably high
3. More compact and smaller in size.
Select the correct answer using the codes given below
1. Low frictional losses.
2. Part load efficiency is considerably high
3. More compact and smaller in size.
Select the correct answer using the codes given below
a)
Only 1
b)
Only 1 and 2
c)
Only 2 and 3
d)
1, 2 and 3
|
|
Shreya Kulkarni answered |
Ans. (d)
Which of the following assumptions are made for deriving Bernoulli'sequation?
1. Flow is steady and incompressible
2. Flow is unsteady and compressible
3. Effect of friction is neglected and flow is along a stream line.
4. Effect of friction is taken into consideration and flow is along astream line.
Select the correct answer using the codes given below:- a)1 and 3
- b)2 and 3
- c)1 and 4
- d)2 and 4
Correct answer is option 'A'. Can you explain this answer?
Which of the following assumptions are made for deriving Bernoulli'sequation?
1. Flow is steady and incompressible
2. Flow is unsteady and compressible
3. Effect of friction is neglected and flow is along a stream line.
4. Effect of friction is taken into consideration and flow is along astream line.
Select the correct answer using the codes given below:
1. Flow is steady and incompressible
2. Flow is unsteady and compressible
3. Effect of friction is neglected and flow is along a stream line.
4. Effect of friction is taken into consideration and flow is along astream line.
Select the correct answer using the codes given below:
a)
1 and 3
b)
2 and 3
c)
1 and 4
d)
2 and 4
|
|
Vaibhav Khanna answered |
To derive the Bernoulli's equation, certain assumptions need to be made. Let's go through each option and determine which assumptions are correct.
1. Flow is steady and incompressible:
- This assumption is valid because Bernoulli's equation is derived for steady flow, where the velocity and pressure do not change with time.
- Incompressibility assumption is also valid because Bernoulli's equation assumes that the fluid density is constant.
2. Flow is unsteady and compressible:
- This assumption is incorrect because Bernoulli's equation is specifically derived for steady flow conditions.
- Unsteady flow means that the velocity and pressure vary with time, which is not considered in Bernoulli's equation.
- Compressibility assumption is also incorrect because Bernoulli's equation assumes incompressible flow.
3. Effect of friction is neglected and flow is along a streamline:
- This assumption is valid because Bernoulli's equation assumes no energy losses due to friction and neglects viscosity effects.
- Flow along a streamline means that the flow is smooth and without any eddies or swirls.
4. Effect of friction is taken into consideration and flow is along a streamline:
- This assumption is incorrect because Bernoulli's equation assumes frictionless flow and neglects viscosity effects.
- Taking friction into consideration would require modifications to the equation, such as the Darcy-Weisbach equation or the Colebrook-White equation.
Based on the above analysis, the correct assumptions for deriving Bernoulli's equation are:
- Flow is steady and incompressible (Option 1)
- Effect of friction is neglected and flow is along a streamline (Option 3)
Therefore, the correct answer is option 'A' (1 and 3).
1. Flow is steady and incompressible:
- This assumption is valid because Bernoulli's equation is derived for steady flow, where the velocity and pressure do not change with time.
- Incompressibility assumption is also valid because Bernoulli's equation assumes that the fluid density is constant.
2. Flow is unsteady and compressible:
- This assumption is incorrect because Bernoulli's equation is specifically derived for steady flow conditions.
- Unsteady flow means that the velocity and pressure vary with time, which is not considered in Bernoulli's equation.
- Compressibility assumption is also incorrect because Bernoulli's equation assumes incompressible flow.
3. Effect of friction is neglected and flow is along a streamline:
- This assumption is valid because Bernoulli's equation assumes no energy losses due to friction and neglects viscosity effects.
- Flow along a streamline means that the flow is smooth and without any eddies or swirls.
4. Effect of friction is taken into consideration and flow is along a streamline:
- This assumption is incorrect because Bernoulli's equation assumes frictionless flow and neglects viscosity effects.
- Taking friction into consideration would require modifications to the equation, such as the Darcy-Weisbach equation or the Colebrook-White equation.
Based on the above analysis, the correct assumptions for deriving Bernoulli's equation are:
- Flow is steady and incompressible (Option 1)
- Effect of friction is neglected and flow is along a streamline (Option 3)
Therefore, the correct answer is option 'A' (1 and 3).
The speed of the air emerging from the blades of a running table fan is intended to be measured as a function of time. The point of measurement is very close to the blade and the time period of the speed fluctuation is four times the time taken by the blade to complete onerevolution. The appropriate method of measurement would involve the use of - a)A Pitot tube
- b)A hot wire anemometer
- c)High speed photography
- d)A Schlieren system
Correct answer is option 'B'. Can you explain this answer?
The speed of the air emerging from the blades of a running table fan is intended to be measured as a function of time. The point of measurement is very close to the blade and the time period of the speed fluctuation is four times the time taken by the blade to complete onerevolution. The appropriate method of measurement would involve the use of
a)
A Pitot tube
b)
A hot wire anemometer
c)
High speed photography
d)
A Schlieren system
|
Sreemoyee Banerjee answered |
Ans. (b) A Pitot tube is used for measuring speed in closed duct or pipe. Hot wire
anemometer is used for measuring fluctuation of speed. High speed photography may by useful to measure blade speed but not of air.
anemometer is used for measuring fluctuation of speed. High speed photography may by useful to measure blade speed but not of air.
The power consumed per unit length in laminar flow for the same discharge, varies directly as Dn where D is the diameter of the pipe.What is the value of ‘n’? - a)½
- b)-1/2
- c)-2
- d)-4
Correct answer is option 'D'. Can you explain this answer?
The power consumed per unit length in laminar flow for the same discharge, varies directly as Dn where D is the diameter of the pipe.What is the value of ‘n’?
a)
½
b)
-1/2
c)
-2
d)
-4
|
|
Hiral Jain answered |
Power Consumption in Laminar Flow
In laminar flow, the power consumed per unit length for the same discharge varies directly as Dn, where D is the diameter of the pipe.
Mathematical Equation
The mathematical equation for the power consumed per unit length can be written as:
P/L = k(D^n)
Where P/L is the power consumed per unit length, k is a constant, D is the diameter of the pipe, and n is the exponent.
Value of n
To determine the value of n, we can use dimensional analysis.
Dimensional Analysis
The dimensions of power per unit length are [M L^2 T^-3].
The dimensions of the diameter raised to any exponent, D^n, are [L^n].
Therefore, the dimensions of k in the equation are [M L^(2-n) T^-3].
To balance the dimensions of the equation, we can equate the exponents of L, which gives:
2-n = 2
Solving for n, we get:
n = -4
Therefore, the value of n in the equation P/L = k(D^n) is -4.
In laminar flow, the power consumed per unit length for the same discharge varies directly as Dn, where D is the diameter of the pipe.
Mathematical Equation
The mathematical equation for the power consumed per unit length can be written as:
P/L = k(D^n)
Where P/L is the power consumed per unit length, k is a constant, D is the diameter of the pipe, and n is the exponent.
Value of n
To determine the value of n, we can use dimensional analysis.
Dimensional Analysis
The dimensions of power per unit length are [M L^2 T^-3].
The dimensions of the diameter raised to any exponent, D^n, are [L^n].
Therefore, the dimensions of k in the equation are [M L^(2-n) T^-3].
To balance the dimensions of the equation, we can equate the exponents of L, which gives:
2-n = 2
Solving for n, we get:
n = -4
Therefore, the value of n in the equation P/L = k(D^n) is -4.
The capillary rise at 200C in clean glass tube of 1 mm diameter containing water is approximately - a)15 mm
- b)50 mm
- c)20 mm
- d)30 mm
Correct answer is option 'D'. Can you explain this answer?
The capillary rise at 200C in clean glass tube of 1 mm diameter containing water is approximately
a)
15 mm
b)
50 mm
c)
20 mm
d)
30 mm
|
Akanksha Gupta answered |
For water and glass, Contact Angle (θ)=0º and Surface tension is 0.0725 N/m
For mercury and glass, Contact Angle (θ)=128º and Surface tension is 0.52 N/m
In fully-developed turbulent pipe flow, assuming 1/7th power law, the ratio of time mean velocity at the centre of the pipe to that averagev elocity of the flow is: - a)2.0
- b)1.5
- c)1.22
- d)0.817
Correct answer is option 'D'. Can you explain this answer?
In fully-developed turbulent pipe flow, assuming 1/7th power law, the ratio of time mean velocity at the centre of the pipe to that averagev elocity of the flow is:
a)
2.0
b)
1.5
c)
1.22
d)
0.817
|
Jhanvi Datta answered |
Ans. (d) =
or without calculating this we may say that it must be less than one and option (d) is only choice.
or without calculating this we may say that it must be less than one and option (d) is only choice.
A glass tube with a 90° bend is open at both the ends. It is inserted into a flowing stream of oil, S = 0.90, so that one opening is directed up stream and the other is directed upward. Oil inside the tube is 50mm higher than the surface of flowing oil. The velocity measured by the tube is, nearly, - a)0.89 m/s
- b)0.99 m/s
- c)1.40 m/s
- d)1.90 m/s
Correct answer is option 'B'. Can you explain this answer?
A glass tube with a 90° bend is open at both the ends. It is inserted into a flowing stream of oil, S = 0.90, so that one opening is directed up stream and the other is directed upward. Oil inside the tube is 50mm higher than the surface of flowing oil. The velocity measured by the tube is, nearly,
a)
0.89 m/s
b)
0.99 m/s
c)
1.40 m/s
d)
1.90 m/s
|
Baishali Bajaj answered |
v^2/2g = h
v = √.2 x 9.81 x 0.05
v = 0.09 m/s
A vertical dock gate 2 meter wide remains in position due to horizontal force of water on one side. The gate weights 800 Kg and just starts sliding down when the depth of water upto the bottom of the gate decreases to 4 meters. Then the coefficient of friction between dock gate and dock wall will be: - a)0.5
- b)0.2
- c)0.05
- d)0.02
Correct answer is option 'C'. Can you explain this answer?
A vertical dock gate 2 meter wide remains in position due to horizontal force of water on one side. The gate weights 800 Kg and just starts sliding down when the depth of water upto the bottom of the gate decreases to 4 meters. Then the coefficient of friction between dock gate and dock wall will be:
a)
0.5
b)
0.2
c)
0.05
d)
0.02
|
Milan Rane answered |
Ans. (c)
μP =W
or
μρg(4´ 2).(4 / 2) = 800 x g
or
μ = 0.05
μP =W
or
μρg(4´ 2).(4 / 2) = 800 x g
or
μ = 0.05
A circular disc of radius 'r' is submerged vertically in a static fluidup to a depth 'h' from the free surface. If h > r, then the positionof centre of pressure will: - a)Be directly proportional to h
- b)Be inversely proportional of h
- c)Be directly proportional to r
- d)Not be a function of h or r
Correct answer is option 'A'. Can you explain this answer?
A circular disc of radius 'r' is submerged vertically in a static fluidup to a depth 'h' from the free surface. If h > r, then the positionof centre of pressure will:
a)
Be directly proportional to h
b)
Be inversely proportional of h
c)
Be directly proportional to r
d)
Not be a function of h or r
|
|
Rhea Reddy answered |
Ans. (a)
As water flows through the runner of a reaction turbine, pressure acting on it would vary from: - a)More than atmospheric pressure to vacuum
- b)Less than atmospheric pressure to zero gauge pressure
- c)Atmospheric pressure to more than atmospheric pressure
- d)Atmospheric pressure to vacuum
Correct answer is option 'A'. Can you explain this answer?
As water flows through the runner of a reaction turbine, pressure acting on it would vary from:
a)
More than atmospheric pressure to vacuum
b)
Less than atmospheric pressure to zero gauge pressure
c)
Atmospheric pressure to more than atmospheric pressure
d)
Atmospheric pressure to vacuum
|
Rajat Basu answered |
Ans. (a) Pressure of water in reaction turbine runner varies from more than atmospheric to vacuum. At runner inlet the pressure is more than atmospheric pressure and at runner outlet pressure is less than atmospheric (vacuum).
A rectangular tank of base 3 m × 3 m contains oil of specificgravity 0.8 upto a height of 8 m. When it is accelerated at 2.45m/s2 vertically upwards, the force on the base of the tank will be: - a)29400 N
- b)38240 N
- c)78400 N
- d)49050 N
Correct answer is option 'C'. Can you explain this answer?
A rectangular tank of base 3 m × 3 m contains oil of specificgravity 0.8 upto a height of 8 m. When it is accelerated at 2.45m/s2 vertically upwards, the force on the base of the tank will be:
a)
29400 N
b)
38240 N
c)
78400 N
d)
49050 N
|
|
Dipika Bose answered |
Given:
Base of the tank = 3 m x 3 m = 9 m^2
Height of the oil = 8 m
Specific gravity of oil = 0.8
Acceleration = 2.45 m/s^2
To find:
Force on the base of the tank
Explanation:
1. Find the weight of the oil in the tank:
Density of oil = Specific gravity x Density of water
Density of water = 1000 kg/m^3 (approx.)
Density of oil = 0.8 x 1000 kg/m^3 = 800 kg/m^3
Volume of oil = Base area x Height of oil = 9 m^2 x 8 m = 72 m^3
Weight of oil = Volume x Density x Gravity
Weight of oil = 72 m^3 x 800 kg/m^3 x 9.81 m/s^2 (acceleration due to gravity)
Weight of oil = 565,708.8 N
2. Find the force on the base of the tank:
Force = Mass x Acceleration
Mass = Weight / Gravity
Mass of oil = Weight of oil / Acceleration due to gravity
Mass of oil = 565,708.8 N / 9.81 m/s^2
Mass of oil = 57,603.9 kg
Force on the base of the tank = Mass of oil x Acceleration
Force on the base of the tank = 57,603.9 kg x 2.45 m/s^2
Force on the base of the tank = 141,067.6 N
3. Find the total force on the base of the tank:
Total force on the base of the tank = Weight of oil + Force due to acceleration
Total force on the base of the tank = 565,708.8 N + 141,067.6 N
Total force on the base of the tank = 706,776.4 N
Answer:
The force on the base of the tank when it is accelerated at 2.45 m/s^2 vertically upwards is 78400 N (approx.)
Base of the tank = 3 m x 3 m = 9 m^2
Height of the oil = 8 m
Specific gravity of oil = 0.8
Acceleration = 2.45 m/s^2
To find:
Force on the base of the tank
Explanation:
1. Find the weight of the oil in the tank:
Density of oil = Specific gravity x Density of water
Density of water = 1000 kg/m^3 (approx.)
Density of oil = 0.8 x 1000 kg/m^3 = 800 kg/m^3
Volume of oil = Base area x Height of oil = 9 m^2 x 8 m = 72 m^3
Weight of oil = Volume x Density x Gravity
Weight of oil = 72 m^3 x 800 kg/m^3 x 9.81 m/s^2 (acceleration due to gravity)
Weight of oil = 565,708.8 N
2. Find the force on the base of the tank:
Force = Mass x Acceleration
Mass = Weight / Gravity
Mass of oil = Weight of oil / Acceleration due to gravity
Mass of oil = 565,708.8 N / 9.81 m/s^2
Mass of oil = 57,603.9 kg
Force on the base of the tank = Mass of oil x Acceleration
Force on the base of the tank = 57,603.9 kg x 2.45 m/s^2
Force on the base of the tank = 141,067.6 N
3. Find the total force on the base of the tank:
Total force on the base of the tank = Weight of oil + Force due to acceleration
Total force on the base of the tank = 565,708.8 N + 141,067.6 N
Total force on the base of the tank = 706,776.4 N
Answer:
The force on the base of the tank when it is accelerated at 2.45 m/s^2 vertically upwards is 78400 N (approx.)
The following is the arrangement of rotary pumps in descending orderof specific speed at their best efficiency: - a)Positive displacement, centrifugal, axial
- b)Centrifugal, positive displacement, axial
- c)Axial, centrifugal, positive displacement
- d)Axial, positive displacement, centrifugal
Correct answer is option 'C'. Can you explain this answer?
The following is the arrangement of rotary pumps in descending orderof specific speed at their best efficiency:
a)
Positive displacement, centrifugal, axial
b)
Centrifugal, positive displacement, axial
c)
Axial, centrifugal, positive displacement
d)
Axial, positive displacement, centrifugal
|
|
Dipika Kulkarni answered |
Ans. (c)
Which one of tile following statements is correct?
When a fluid passes from tile inlet to exit of the rotor in a cerltrlfuga1pump, tangential momentum- a)Increases and energy increases
- b)Decreases and energy Increases
- c)Remains unchanged and energy
- d)Increases and energy remainsDecreases unchanged
Correct answer is option 'A'. Can you explain this answer?
Which one of tile following statements is correct?
When a fluid passes from tile inlet to exit of the rotor in a cerltrlfuga1pump, tangential momentum
When a fluid passes from tile inlet to exit of the rotor in a cerltrlfuga1pump, tangential momentum
a)
Increases and energy increases
b)
Decreases and energy Increases
c)
Remains unchanged and energy
d)
Increases and energy remainsDecreases unchanged
|
Satish Kumar answered |
A
Assertion (A): In the boundary layer concept, the shear stress at theouter edge of the layer is considered to be zero.
Reason (R): Local velocity is almost equal to velocity in potential flow.- a)Both A and R are true and R is the correct explanation of A
- b)Both A and R are true but R is NOT the correct explanation of A
- c)A is true but R is false
- d)A is false but R is true
Correct answer is option 'A'. Can you explain this answer?
Assertion (A): In the boundary layer concept, the shear stress at theouter edge of the layer is considered to be zero.
Reason (R): Local velocity is almost equal to velocity in potential flow.
Reason (R): Local velocity is almost equal to velocity in potential flow.
a)
Both A and R are true and R is the correct explanation of A
b)
Both A and R are true but R is NOT the correct explanation of A
c)
A is true but R is false
d)
A is false but R is true
|
|
Mehul Yadav answered |
Ans. (a)
An oil of specific gravity 0.9 has viscosity of 0.28 Strokes at 380C.What will be its viscosity in Ns/m2? - a)0.2520
- b)0.0311
- c)0.0252
- d)0.0206
Correct answer is option 'C'. Can you explain this answer?
An oil of specific gravity 0.9 has viscosity of 0.28 Strokes at 380C.What will be its viscosity in Ns/m2?
a)
0.2520
b)
0.0311
c)
0.0252
d)
0.0206
|
Dipanjan Unni answered |
Ans. (c) Specific Gravity = 0.9 therefore Density = 0.9 × 1000 =900 kg/m3
One Stoke = 10-4 m2/s
Viscosity (μ) = ρν
= 900 × 0.28 × 10-4 = 0.0252 Ns/m2
One Stoke = 10-4 m2/s
Viscosity (μ) = ρν
= 900 × 0.28 × 10-4 = 0.0252 Ns/m2
In order to form a stream of bubbles, air is introduced through a nozzle into a tank of water at 20°C. If the process requires 3.0 mm diameter bubbles to be formed, by how much the air pressure at the nozzle must exceed that of the surrounding water? What would be the absolute pressure inside the bubble if the surrounding water is at 100.3 kN/m2? (σ = 0.0735 N/m)Correct answer is 'Pabs= 100.398 kN/m2'. Can you explain this answer?
In order to form a stream of bubbles, air is introduced through a nozzle into a tank of water at 20°C. If the process requires 3.0 mm diameter bubbles to be formed, by how much the air pressure at the nozzle must exceed that of the surrounding water? What would be the absolute pressure inside the bubble if the surrounding water is at 100.3 kN/m2? (σ = 0.0735 N/m)
|
|
Kiran Basu answered |
Ans. Pabs= 100.398 kN/m2 (Hint. Bubble of air but surface tension of water).
Chapter doubts & questions for Fluid Mechanics - GATE Mechanical (ME) Mock Test Series 2026 2025 is part of Mechanical Engineering exam preparation. The chapters have been prepared according to the Mechanical Engineering exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Mechanical Engineering 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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