What is the primary property of a fluid that determines its resistance to flow?
A Pressure
B Temperature
C Density
D Viscosity
Viscosity is the internal friction within a fluid that resists its flow. It is a measure of a fluid’s “thickness” or resistance to shear forces. Fluids with higher viscosity flow slower compared to those with lower viscosity.
What does Bernoulli’s equation primarily describe?
A Energy conservation
B Fluid velocity
C Flow rate
D Fluid pressure
Bernoulli’s equation represents the conservation of mechanical energy for a flowing fluid. It states that the total energy (sum of pressure energy, kinetic energy, and potential energy) remains constant along a streamline for an incompressible, non-viscous fluid.
In which type of flow is the fluid velocity uniform across any cross section?
A Steady flow
B Laminar flow
C Turbulent flow
D Compressible flow
In laminar flow, the fluid moves smoothly in layers, with each layer moving in parallel. The velocity is uniform across any cross section, and there is no mixing between layers, in contrast to turbulent flow, which is chaotic and irregular.
What does Reynolds number indicate in fluid flow?
A Fluid density
B Temperature change
C Pressure difference
D Flow pattern
Reynolds number is a dimensionless number used to predict the flow regime in a fluid. It helps determine whether the flow is laminar or turbulent. A low Reynolds number indicates laminar flow, while a high number indicates turbulent flow.
What is the cause of buoyant force on an object submerged in a fluid?
A Weight of fluid
B Fluid’s density
C Pressure difference
D Fluid’s viscosity
Buoyant force arises due to the difference in pressure exerted on the object by the fluid at different depths. The pressure at the bottom is higher than at the top, resulting in an upward force that is equal to the weight of the displaced fluid.
What is the flow rate in a pipe when the velocity is constant and the pipe diameter changes?
A Stays the same
B Depends on the fluid
C Decreases
D Increases
According to the continuity equation, the flow rate (Q) is constant for an incompressible fluid. When the diameter of the pipe changes, the velocity adjusts accordingly to maintain the same flow rate, ensuring the mass flow rate remains constant.
What is the characteristic of a compressible fluid?
A Viscous
B Incompressible
C Constant density
D Pressure changes with density
A compressible fluid is one in which the fluid density changes significantly with pressure. Air, for example, is a compressible fluid because its density varies substantially when subjected to pressure changes, unlike incompressible fluids like water.
What does the Navier-Stokes equation describe?
A Heat transfer
B Energy conservation
C Fluid motion
D Pressure changes
The Navier-Stokes equations describe the motion of viscous fluid substances. They are a set of nonlinear partial differential equations that provide a mathematical model for fluid dynamics, accounting for factors like viscosity, velocity, and external forces.
Which of these is a measure of how fluid flows through porous materials?
A Darcy’s law
B Reynolds number
C Navier-Stokes equation
D Bernoulli’s equation
Darcy’s law is used to describe the flow of a fluid through a porous medium. It is crucial in fields like hydrogeology and petroleum engineering, where it helps to model groundwater flow or oil extraction.
What is the main cause of cavitation in a pump?
A High viscosity
B Low pressure
C High temperature
D High velocity
Cavitation occurs when the local pressure in a fluid falls below its vapor pressure, causing the fluid to vaporize and form bubbles. These bubbles collapse violently when they move to higher pressure areas, leading to damage in pumps and other equipment.
Which of the following factors affects the drag force on an object moving through a fluid?
A Shape and speed
B Fluid’s density only
C Fluid’s temperature
D Object’s color
Drag force is primarily affected by the shape of the object and its speed relative to the fluid. The smoother and more streamlined the object, the less drag it will experience. Increased speed generally increases the drag force.
What is the purpose of boundary layers in fluid flow?
A Decrease pressure
B Increase velocity
C Separate fluids
D Reduce friction
Boundary layers are thin regions near the surface of an object where the fluid velocity changes from zero (at the surface) to the free-stream velocity. They help reduce friction and resistance between the surface and the fluid flow.
What kind of fluid flow is associated with irregular, chaotic motion and vortices?
A Uniform flow
B Steady flow
C Turbulent flow
D Laminar flow
Turbulent flow is characterized by irregular, chaotic fluid motion, with eddies and vortices forming in the flow. This type of flow typically occurs at high velocities or in fluids with high Reynolds numbers.
In a hydraulic system, what is used to transmit force?
A Incompressible fluids
B Air
C Viscous fluids
D Compressible fluids
Hydraulic systems use incompressible fluids like oil or water to transmit force. The incompressibility ensures that the pressure applied to one part of the system is efficiently transferred to other parts, allowing for precise force control.
What is a streamline in fluid mechanics?
A Pressure point
B Path of fluid particles
C Fluid boundary
D Velocity change
A streamline is a curve that represents the path followed by a fluid particle in steady flow. Streamlines never cross each other and are used to visualize the flow of fluid, showing how the velocity and direction of the fluid vary throughout the flow.