Fluid Mechanics JEE Advance Previous Year Questions with Solutions and Weightage

In JEE Advanced Physics, Fluid mechanics is considered to be a moderate topic, carrying a weightage of around 5% with 2-3 questions asked each year. Most of the questions are conceptual based which focuses on fluids.

Fluid mechanics is defined as the division of engineering science which deals with the behaviour of the fluid in both motion and rest situations. It is one of the four divisions of mechanics namely quantum mechanics, relative mechanism, fluid mechanics and elastic body mechanics.

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• Download JEE Advanced Syllabus 2025
• Download JEE Advanced 2024 Paper With Detailed Solutions
• JEE Advanced Previous Year Question Paper PDF Download

Listed below is the list of Fluid Mechanics questions with detailed solutions asked in JEE Advanced exam 2025:

Question 1:

A table tennis ball has radius (3/2)×10−2m and mass (22/7)×10−3 kg. It is slowly pushed down into a swimming pool to a depth of ???? = 0.7 m below the water surface and then released from rest. It emerges from the water surface at speed ????, without getting wet, and rises up to a height ????. Which of the following option(s) is(are) correct?[Given: π=22/7,g=10ms−2, density of water = 1×103 kg m−3 , viscosity of water = 1×10−3 Pa-s.]

• The work done in pushing the ball to the depth ???? is 0.077 J
• If we neglect the viscous force in water, then the speed ???? = 7 m/s.
• If we neglect the viscous force in water, then the height ???? = 1.4 m.
• The ratio of the magnitudes of the net force excluding the viscous force to the maximum viscous force in water is 500/9.

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Question 2:

An incompressible liquid is filled in a container. There is air above the liquid and a massless movable piston with a hole is also placed on the air. A thin capillary tube of inner radius 0.1 mm is dipped vertically into the liquid through the hole on the piston as shown in the figure. The air in the container is isothermally compressed from the original volume V0 to 100/110

​

V0 with the movable piston. Considering air as an ideal gas, the height (h) of the liquid column in the capillary above the liquid level in cm is:

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Question 3:

A bubble has surface tension S. The ideal gas inside the bubble has ratio of specific heats γ=5/3. The bubble is exposed to the atmosphere and it always retains its spherical shape. When the atmospheric pressure is Pa1, the radius of the bubble is found to be R1 and the temperature of the enclosed gas is T1. When the atmospheric pressure is Pa2, the radius of the bubble and the temperature of the enclosed gas are r2 and T2, respectively.Which of the following statement(s) is(are) correct?

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Question 4:

A cylindrical tube, with its base as shown in the figure, is filled with water It is moving down with a constant acceleration a along a fixed inclined plane with angle θ=45∘P1 and P2 are pressures at points 1 and 2, respectively located at the base of the tube Let β=(P1−P2)/(ρgd), where ρ is density of water, d is the inner diameter of the tube and g is the acceleration due to gravity .

Which of the following statement(s) is(are) correct?

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Question 5:

One end of a horizontal uniform beam of weight W and length L is hinged on a vertical wall at point O and its other end is supported by a light inextensible rope. The other end of the rope is fixed at point Q, at a height L above the hinge at point O a block of weight αW is attached at the point P of the beam, as shown in the figure (not to scale). The rope can sustain a maximum tension of (22) W. Which of the following statement(s) is(are) correct?

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Question 6:

A soft plastic bottle, filled with water of density 1 gm/cc, carries an inverted glass test tube with some air (ideal gas) trapped as shown in the figure. The test tube has a mass of 5 gm, and it is made of a thick glass of density 2.5 gm/cc. Initially, the bottle is sealed at atmospheric pressure p0 = 105 Pa so that the volume of the trapped air is V0 = 3.3 cc. When the bottle is squeezed from outside at a constant temperature, the pressure inside rises and the volume of the trapped air reduces. It is found that the test tube begins to sink at pressure p0 + Δp without changing its orientation. At this pressure, the volume of the trapped air is V0 – ΔV.

Let ΔV = X cc and Δp = Y × 103 Pa.

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Question 7:

Two large circular discs separated by a distance of 0.01m are connected to a battery via a switch as shown in the figure Charged oil drops of density 900kgm−3 are released through a tiny hole at the center of the top disc Once some oil drops achieve terminal velocity, the switch is closed to apply a voltage of 200V across the discs As a result, an oil drop of radius 8×10 -7m stops moving vertically and floats between the discs The number of electrons present in this oil drop is (neglect the buoyancy force, take acceleration due to gravity =10ms−2 and charge on an electron (e)=1.6×10−19C

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Question 8:

A uniform capillary tube of inner radius r is dipped vertically into a beaker filled with water. The water rises to a height h in the capillary tube above the water surface in the beaker. The surface tension of water is σ. The angle of contact between water and the wall of the capillary tube is θ. Ignore the mass of water in the meniscus. Which of the following statements is (are) true?

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JEE Advanced 2025 Exam Pattern

The JEE Advanced 2025 exam consists of two papers: Paper 1 and Paper 2. Both papers are compulsory and must be attempted by the candidates. The exam will be conducted online (computer-based).

Subject-wise Syllabus: JEE Advanced 2025

The JEE Advanced 2025 Subject-wise syllabus covers important topics across Physics, Chemistry, and Mathematics, with each subject focusing on advanced concepts.

• Mathematics focuses on concepts - Calculus and Algebra.
• Physics emphasis on Mechanics and Electrodynamics, while Chemistry includes topics like Physical Chemistry and Organic Chemistry.
• According to past analysis, Mathematics often carries the highest weightage.

JEE Advanced Chapter-wise Weightage

The JEE Advanced chapter-wise weightage helps you understand topics that carry more importance in the exam. By focusing on high-weightage chapters, you can improve your preparation. For example, in Mathematics, topics like Calculus and Algebra usually cover 50-60% of the questions, while in Physics, Mechanics and Electromagnetism contribute more.

JEE Advanced Physics - Weightage and Important Topics

• Mechanics (particularly Kinematics and Laws of Motion) have a higher weightage, often constituting a major chunk of the Physics paper.
• Modern Physics, with topics like the Photoelectric Effect and Nuclear Physics, remains significant with high-scoring potential.
• Physical Chemistry and Organic Chemistry both have a large weightage. Topics like Chemical Kinetics and Reaction Mechanisms in Organic Chemistry are crucial and frequently asked.
• Inorganic Chemistry remains a reliable scoring area with an emphasis on Periodic Table and Coordination Compounds.

JEE Advanced 2025: Subject-wise Weightage

• Mathematics holds the highest weightage, so mastering Calculus and Algebra is critical.
• Physics and Chemistry both have significant portions dedicated to Mechanics and Physical Chemistry, respectively.
• Regular practice of important topics like Modern Physics, Organic Chemistry, and Coordinate Geometry can help candidates maximize their scores in JEE Advanced 2025.

To find the Minimum Marks Required to Qualify JEE Advanced 2025, it's also important to understand the category-wise cutoff criteria set by the exam authorities.

Previous Years’ Question Paper

JEE Advanced 2024 Question Paper PDF

JEE Advanced 2023 Question Paper PDF

JEE Advanced 2022 Question Paper PDF

JEE Advanced 2021 Question Paper PDF

JEE Advanced 2020 Question Paper

Frequently Asked Questions:

Which fluid mechanics topics are most frequently asked in JEE Advanced?

The topics that are most frequently asked are fluid statics (fluids at rest), fluid dynamics (fluids in motion), with subtopics like viscosity, pressure, and density, and further specialized fields like aerodynamics and hydrodynamics.

What are common mistakes students make in buoyancy problems?

Mistakes that are common in buoyancy questions by misapplying Archimedes' principle, confusing buoyancy with density, and failing to account for the volume of displaced fluid.

Some key points on Buoyancy :

i. Buoyant force (on a fully-submerged object) is greater for objects of greater mass but same volume.

ii. Buoyant force (on a fully-submerged object) increases/decreases with depth in the fluid.

iii. Buoyant force depends upon the amount of fluid in the container.

iv. Buoyant force depends upon orientation or shape of constant-volume object.

v. Buoyant force depends upon other forces acting on the object.

What is 110 marks in JEE Advanced exam?

The top-ranked candidates across all categories are expected to score significantly higher compared to the last-ranked candidates. For example, the first-ranked CRL candidate is expected to score around 360 marks, while the last-ranked candidate in CRL might only score around 110 marks, indicating a large gap in performance between the highest and lowest qualifiers.

Marks vs Rank Analysis (Previous Year Trends):

While the exact ranks depend on the exam's difficulty level, here's a general idea based on past year trends: