Basic Mechanical Engineering - BT203

BME Unit 3: Fluids

Complete RGPV exam-oriented page covering fluid properties, density, pressure, viscosity, Newton's law of viscosity, Pascal's law, Bernoulli's equation, hydraulic machines, pumps, turbines and reciprocating pump.

Read Notes Important Questions PYQ Analysis

Unit 3 Syllabus

Fluids important topics

Fluid Basics

  • Fluid properties
  • Pressure, density and viscosity
  • Types of fluids
  • Ideal and real fluids

Important Laws

  • Newton's law of viscosity
  • Pascal's law
  • Bernoulli's equation
  • Applications of Bernoulli theorem

Hydraulic Machines

  • Pumps
  • Turbines
  • Reciprocating pumps
  • Centrifugal pump

Short Exam Notes

Easy points for fast revision

Fluid

A fluid is a substance which flows continuously when external force is applied. Examples are water, oil and air.

Density

Density is mass per unit volume of fluid. Its unit is kg/m³. It is used to compare heaviness of different fluids.

Pressure

Pressure is force acting per unit area. Its SI unit is Pascal or N/m².

Viscosity

Viscosity is the property of fluid which resists relative motion between layers. Honey has high viscosity and water has low viscosity.

Newton's Law of Viscosity

Newton's law states that shear stress is directly proportional to velocity gradient. It is mainly used in lubrication and fluid flow analysis.

Pascal's Law

Pascal's law states that pressure applied at any point of a confined fluid is transmitted equally in all directions. It is used in hydraulic press, lift and brakes.

Bernoulli's Equation

Bernoulli's theorem states that total energy of flowing incompressible fluid remains constant. It is used in venturimeter, aircraft wings and carburetor.

Reciprocating Pump

Reciprocating pump is a positive displacement pump in which piston moves back and forth inside a cylinder. It is suitable for high pressure applications.

Quick Revision Formulas

Important numerical formulas

Density: ρ = m / V
Pressure: P = F / A
Newton's Law of Viscosity: τ = μ(du/dy)
Bernoulli's Equation: P/ρg + V²/2g + z = Constant

Most Important Questions

High chance RGPV exam questions

14 Marks Questions

  • Explain fluid properties with suitable examples.
  • Explain density, pressure and viscosity in detail.
  • Explain different types of fluids with examples.
  • State and explain Newton's law of viscosity.
  • State and explain Pascal's law with applications.
  • Derive Bernoulli's equation for incompressible fluids.
  • Explain assumptions and applications of Bernoulli's theorem.
  • Explain hydraulic machines and their classification.
  • Explain working principle of pumps and turbines.
  • Explain reciprocating pump with neat diagram and working principle.

7 Marks Questions

  • Define density and pressure.
  • Explain viscosity and its importance.
  • Explain ideal and real fluids.
  • Explain Newtonian and non-Newtonian fluids.
  • Explain Pascal's law applications.
  • Explain Bernoulli's theorem.
  • Explain hydraulic machines.
  • Explain centrifugal pump.

Important Numericals

  • Pressure calculation numerical problems
  • Density numerical calculations
  • Bernoulli equation numerical problems
  • Fluid flow calculation problems
  • Viscosity related numerical problems

PYQ Analysis Table

Repeated questions from previous RGPV papers

Topic Repeated Questions Frequency Priority
Bernoulli's Equation Derivation, assumptions, applications and numerical problems Very High ★★★★★
Pascal's Law Statement, hydraulic press, hydraulic lift and applications Very High ★★★★★
Fluid Properties Density, pressure, viscosity and significance Very High ★★★★★
Reciprocating Pump Neat sketch, working principle and applications High ★★★★
Hydraulic Machines Classification and industrial applications High ★★★★
Viscosity Newton's law of viscosity and types of fluids High ★★★★
Pumps Centrifugal pump and reciprocating pump working Medium ★★★
Turbines Working principle and applications in power plants Medium ★★★

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FAQs

Common student doubts

Which topic is most important in BME Unit 3?

Bernoulli's equation, Pascal's law, fluid properties, reciprocating pump and hydraulic machines are most important.

Which numericals should I practice?

Pressure, density, Bernoulli equation, fluid flow and viscosity numericals are important.

Which diagrams are important?

Reciprocating pump, pumps, turbines, hydraulic press and hydraulic lift diagrams are important.

Related Units

Unit 1 Unit 2 Unit 4 Unit 5