Fluid Dynamics, What Is Fluid Dynamics, Applications of Fluid Dynamics, Bernoulli equation.
In physics, Physics Fluid Dynamics is a core discipline concerned with the movement of fluids (i.e. liquids and gases). It has an essential role in all scientific and engineering domains, affecting everything from aerodynamics to medical sciences. It covers fundamental principles, including viscosity, Bernoulli’s equation, and streamline flow, making it an important topic for students gearing up for the ECAT entry test.
Understanding Physics Fluid Dynamics
Physics Fluid Dynamics studies the flow of fluids and the forces on them. How it works is dictated by basic laws, such as the conservation of mass, energy, and momentum. Fluid motion is generally classified as one of two types.
- Laminar Flow (Streamline Flow) – Fluid particles move in parallel layers without disruption.
- Turbulent Flow – Chaotic movement where fluid layers mix due to varying velocity and pressure.
Key Concepts in Physics Fluid Dynamics
Viscosity and Its Role
Viscosity is a measure of a fluid’s viscous resistance to flow. High-viscosity fluids such as honey move slowly, while low-viscosity fluids like water flow freely. The viscosity is measured by N·s/m².
- Example: The viscosity of ethanol at 30°C is 0.954 × 10⁻³ N·s/m².
- Stokes’ Law explains the drag force acting on a sphere moving through a fluid:
F = 6πηrv
Bernoulli’s Equation and Its Applications
Bernoulli’s principle states that an increase in the speed of fluid results in a decrease in pressure. The equation is: P + ½ρV² + ρgh = constant
- Used in aerodynamics, medical sciences, and fluid mechanics.
- Applied in devices like venturi meters, blood flow measurement, and airplane wing designs.
Equation of Continuity
The equation of continuity expresses the conservation of mass in fluid flow: A₁V₁ = A₂V₂
It indicates that if a fluid moves through a narrowing pipe, its velocity increases, ensuring mass conservation.
Applications of Physics Fluid Dynamics in ECAT Exam
Physics Fluid Dynamics has practical applications in real-world scenarios, making it an essential topic for ECAT entry test aspirants. Some important applications include:
- Aerodynamics – Used in designing cars, airplanes, and rockets.
- Blood Flow in the Human Body – Understanding pressure differences in veins and arteries.
- Engineering and Hydraulics – Designing pipelines, turbines, and water transport systems.
Entry Test Physics Fluid Dynamics MCQS Online Preparation Sample Paper 1 Questions with Answer
1. The viscosity of a fluid is described by
- None of these
- Flowing speed of fluid
- Resistive forces of fluid
- The frictional effect between different layers of a fluid correct
2. Viscosity of ethanol at 30⁰C in Nsm¯²
- 0.954 x 10¯³
- 1.000 x 10¯³ correct
- 1.012 x 10¯³
- 1.014 x 10¯³
3. Viscosity of water at 30⁰C in Nsm¯²
- 0.711 x 10¯³
- 0.812 x 10¯³
- 0.787 x 10¯³
- 0.801 x 10¯³ correct
4. The Bernoulli’s equation is based on the
- Law of conservation of momentum
- Law of conservation of mass
- Law of conservation of energy correct
- None of these
5. Substances that flow easily have a coefficient of viscosity as
- Very large
- Large
- Very Small
- Small correct
6. The drag force F on a sphere of radius ‘r’ moving slowly with speed V through a fluid of viscosity η by Stake’s law?
- F = 6πηrω
- F = 6πηrv correct
- F = πηra
- F = 6πηrav
7. The study of fluids is relatively complicated; this can be simplified by using
- A and B correct
- Law of conservation of mass
- Law of conservation of momentum
- Law of conservation of energy
8. At high speeds the force is no longer
- Simply proportional correct
- Proportional
- No proportion
- None of these
9. The equation of continuity of fluid is based on the
- Law of conservation of energy
- All of these
- Law of conservation of mass correct
- Law of conservation of momentum
10. Even the small viscosity of the air causes a retarding force on the car at high speed is
- Large correct
- Small
- Very large
- None of these
11. Viscosity of acetone at 30⁰C in Nsm¯²
- 0.295 x 10¯³ correct
- 0.198 x 10¯³
- 0.301 x 10¯³
- 0.224 x 10¯³
12. A retarding force experienced by an object, when it moves through a liquid is called
- Drag force correct
- Restoring force
- Applied force
- All of these
13. Viscosity of methanol at 30⁰C in Nsm¯²
- 0.357 x 10¯³
- 0.369 x 10¯³
- 0.341 x 10¯³
- 0.510 x 10¯³ correct
14. Substances that flow easily are
- Petrol
- Kerosene oil
- All of these correct
- Water
15. Substances that do not easily flow have ca coefficient of viscosity as
- Very small
- Large correct
- Small
- None of these
16. Substances that don’t flow easily are
- All of these correct
- Mobile oil
- Thick tar
- Honey
17. Viscosity of plasma at 30⁰C in Nsm¯²
- 1.67 x 10¯³
- 1.595 x 10¯³
- 1.6 x 10¯³ correct
- 1.96 x 10¯³
18. Viscosity of air at 30⁰C in Nsm¯²
- 0.015 x 10¯³
- 0.151 x 10¯³
- 0.019 x 10¯³ correct
- 0.0179 x 10¯³
19. Viscosity of water at 30⁰C in Nsm¯²
- 0.594 x 10¯³
- 0.599 x 10¯³
- 0.521 x 10¯³
- 0.564 x 10¯³ correct
20. The drag force increases as the speed of the object
- Decreases rapidly
- None of these
- Decreases
- Increases correct
Entry Test Physics Fluid Dynamics MCQS Online Preparation Sample Paper 2 Questions with Answer
1. The expression for the terminal velocity Vt when the mass of the droplet is considered is
- Vt = 4grp/9η
- Vt = 4gr²p/9η correct
- Vt = 2grp/9η
- Vt = 4gr³p/9η
2. The flow is said to be streamlined or laminar when every particle
- Slowly moves in one direction
- None of these
- Moves along the same path as correct
- Moves in a different direction
3. Every streamline can
- Somewhat cross each other
- Cross each other
- Not cross each other correct
- None of these
4. In ethe quation of continuity, if the fluid is incompressible and the flow is steady, the mass of the fluid is?
- Not conserved
- Somewhat conserved
- None of these
- Conserved correct
5. A water hose of internal diameter of 20 mm discharges. 30 kg of water in 60 sec. Calculate sthe peed of the water (p for water is 1000 kg m¯³)
- 1.6 ms¯¹ correct
- 1.8 ms¯¹
- 1.2 ms¯¹
- 2.1 ms¯¹
6. Above a certain velocity the fluid flow, the motion of the fluid becomes
- Steady
- Irregular
- Unsteady
- B and C correct
7. In Bernoulli’s equation, the work done due to fluid is
- W = (P₂ – P₁) ρ /m
- W = (P₁ – P₂) ρ /m
- W = (P₁ – P₂) m/ρ correct
- W = (P₂ – P₁) m/ρ
8. If r = 1.0 x 10¯⁴m p = 1000 kgms¯³ η = 19 x 10¯⁶ kgm¯¹ s¯¹ find Vt terminal velocity
- 1.1 ms¯¹ correct
- 0.12 x 10¯³ ms¯¹
- 1.02 x 10¯³ ms¯¹
- 1.21 ms¯¹
9. At terminal velocity the net force acting on it is
- None of these
- Minimum
- Zero correct
- Maximum
10. As the droplet accelerates the net force acting on it is
- None of these
- Zero
- Increase
- Decreases correct
11. When the density is constant for the steady flow of incompressible fluid equation of continuity becomes
- ρ₁ m₁ A₁ V₁= ρ₁ m₁ A₂V₂
- A₁ V₁ = A₂ V₂ correct
- None of these
- ρ₁ A₁ V₁ = ρ₂ A₂ V₂
12. Viscosity of glycerin at 30⁰C in Nsm¯²
- 6.12x 10¯³
- 6.79x 10¯³
- 6.18x 10¯³
- 6.29x 10¯³ correct
13. The expression for the terminal velocity Vt is given by
- Vt = mg/36πη
- Vt = mg/6 πηr correct
- Vt= mg/ 6 π²ηr
- Vt = mg/6 πηa
14. The irregular flow of the fluid is called
- Al of these
- Steady flow
- Streamline
- Turbulent flow correct
15. Bernoulli’s equation related to pressure, fluid speed, and height which is?
- Fundamental equation correct
- Principal equation
- An important equation
- None of these
16. As the droplet accelerates, the upward drag force on it
- Increases correct
- Suspended
- None of these
- Decreases
17. When the fluid is incompressible, for which the density is
- Change
- Both
- None of these
- Constant correct
18. In relation Vt = 2gr²p/9η. Terminal velocity is directly proportional to
- r
- None of these
- R² correct
- r³
19. In deriving Bernoulli’s equation, it is assumed that the fluid is
- Non-viscous
- In a steady state
- Incompressible
- All of these correct
20. The characteristics of steady flow is
- Streamline
- All of these correct
- Incompressible
- Non-viscous
Entry Test Physics Fluid Dynamics MCQS Online Preparation Sample Paper 3 Questions with Answer
1. The relation P₁ – P₂ = ½ ρV₂² shows the
- Venture relation correct
- Bernoulli’s equation
- None of these
- Torricelli’s theorem
2. The viscosity of red blood cells increases than water is from
- 2 to 3 times
- 4 to 5 times
- 3 to 5 times correct
- 3 to 4 time
3. The blood pressure inside is greater than the
- None of these
- Both of them
- External atmospheric pressure correct
- Internal atmospheric pressure
4. The blood vessels are inflated even in
- None of these
- Relaxed states between heartbeat correct
- Working state between heartbeat
- Occasionally
5. In Torricelli’s theorem, the speed of efflux is equal to
- None of these
- (h₁ – h₂) and falling under gravity correct
- Action of gravity
- h₁ – h₂
6. A tall chimney has the advantage
- Reduce top pressure
- Force
- All of these correct
- The upward flow of smoke
7. V₂ = √2g(h₁ – h₂) shows the
- Equation of continuity
- Torricelli’s correct
- Bernoulli’s theorem
- None of these
8. Blood vessels are not
- Rigid correct
- Flexible
- None of these
- Some times flexible
9. The high blood pressure is known as
- Diastolic
- None of these
- Systolic correct
- High blood pressure
10. The venture meter is a device used to measure the fluid
- Speed correct
- Temperature
- Quantity
- Pressure
11. Blood is an incompressible fluid having a density nearly equal to
- Honey
- None of these
- Milk
- Water correct
12. A car engine is based on the principle of
- None of these
- Bernoulli’s equation
- Verdure relation correct
- Torricelli’s theorem
13. Bernoulli’s equation often expressed in
- P + ½ ρV + ρgh = constant
- P + ½ ρV² + ρgh = constant correct
- P +ρV² + ρgh = constant
- P + ½ ρV² + gh = constant
14. Blood vessels under normal conditions are inflated
- None of these
- Occasionally
- All the times correct
- Some times
15. A result of Bernoulli’s equation is that the pressure will be low where the speed of the fluid is
- None of these
- Very high
- Low
- High correct
16. The high blood pressure is
- 130 torr
- 120 torr correct
- 110 torr
- 100 torr
17. Applying PA + ½ ρVA² = PB+ ½ ρ VB² where VA = 0.20ms¯¹, VB = 2.0 ms¯¹ ρ = 1000 kgm¯³ and we get (PA – PB) is
- 1999 Nm¯²
- 1750 Nm¯²
- 1980 Nm¯² correct
- 1975 Nm¯²
18. When V₁ is approximately zero then Bernoulli’s equation reduces to
- Torricelli’s theorem correct
- Venture relation
- Equation of continuity
- None of these
19. A chimney works best when it is
- Exposed to air currents
- Not tall but wide
- A and B correct
- Tall
20. The concentration of red blood cells in blood is
- ~ 50 % correct
- ~ 40 %
- ~ 30%
- ~ 45 %
Conclusion
Mastering Physics Fluid Dynamics becomes very important for the ECAT candidates who intend to score good marks in their entry test. Such relationship helps in boosting the conceptual level of understanding or also improves problem-solving skills of the students as it holds great significance within engineering, medical sciences, and other sectors of fluid mechanics. Continue doing more MCQs and covering key concepts for better exam preparation.