ETC ETC Hydraulics & Fluid Mechanics 1 — Questions and Answers
Question 1: What is the standard SI unit of pressure?
- Newton (N)
- Pascal (Pa) (Correct answer)
- Bar (bar)
- Joule (J)
Correct answer: Pascal (Pa)
The Pascal (Pa) is the SI unit of pressure, defined as one Newton per square meter (N/m²).
Question 2: Pascal's Law states that pressure applied to a confined, incompressible fluid is:
- Transmitted only upward through the fluid
- Transmitted equally in all directions (Correct answer)
- Lost due to internal friction
- Transmitted only in the direction of applied force
Correct answer: Transmitted equally in all directions
Pascal's Law states that pressure applied to a confined fluid is transmitted undiminished and equally in all directions throughout the fluid.
Question 3: The hydrostatic pressure at depth h in a static fluid is calculated using:
- P = ρgh (Correct answer)
- P = ρg/h
- P = mg/A
- P = F × h
Correct answer: P = ρgh
Hydrostatic pressure P = ρgh, where ρ is fluid density, g is gravitational acceleration, and h is depth below the free surface.
Question 4: Specific gravity of a liquid is defined as the ratio of:
- The liquid's volume to water's volume
- The liquid's density to the density of water at 4°C (Correct answer)
- The liquid's weight to its volume
- The liquid's viscosity to water's viscosity
Correct answer: The liquid's density to the density of water at 4°C
Specific gravity is the dimensionless ratio of a substance's density to the density of fresh water (1,000 kg/m³ at 4°C).
Question 5: Which fluid property describes internal resistance to flow (shear deformation)?
- Density
- Specific weight
- Viscosity (Correct answer)
- Surface tension
Correct answer: Viscosity
Viscosity is the property that quantifies a fluid's resistance to shear stress and flow; high-viscosity fluids like motor oil flow more slowly than low-viscosity fluids like water.
Question 6: Bernoulli's equation expresses conservation of which fundamental quantity along a streamline?
- Mass
- Momentum
- Energy (Correct answer)
- Volume
Correct answer: Energy
Bernoulli's equation is a statement of conservation of energy, balancing pressure head, velocity head, and elevation head at any two points along a streamline.
Question 7: The continuity equation for steady incompressible flow in a pipe states that:
- Pressure is constant along the pipe
- Velocity increases as pipe diameter increases
- The product of cross-sectional area and velocity (A₁V₁ = A₂V₂) is constant (Correct answer)
- Flow rate decreases with increasing fluid density
Correct answer: The product of cross-sectional area and velocity (A₁V₁ = A₂V₂) is constant
For incompressible flow, the continuity equation A₁V₁ = A₂V₂ ensures volumetric flow rate Q is constant along the flow path.
ETC ETC Hydraulics & Fluid Mechanics 1
What is the standard SI unit of pressure?