What is the primary cause of buoyant force acting on an object submerged in a fluid?
A Fluid velocity
B Fluid pressure difference
C Object density
D Object shape
Buoyant force is generated by the difference in pressure exerted by the fluid on the object at different depths. The higher pressure at lower depths pushes the object upwards, creating buoyancy.
What does Bernoulli’s equation assume about a fluid’s behavior?
A Viscosity
B Turbulence
C Compressibility
D Steady flow
Bernoulli’s equation assumes steady, incompressible flow without viscosity. It relates pressure, velocity, and elevation, stating that the total mechanical energy of a fluid remains constant along a streamline for these ideal conditions.
What is the relationship between velocity and pressure in a flowing fluid, according to Bernoulli’s principle?
A Exponentially related
B Directly proportional
C Inversely proportional
D No relation
According to Bernoulli’s principle, as the velocity of a fluid increases, its pressure decreases. This is due to the conservation of mechanical energy in the system, where high-speed regions have lower pressure.
What effect does increasing the fluid’s temperature typically have on its viscosity?
A Decreases viscosity
B Fluctuates
C No effect
D Increases viscosity
As the temperature of a fluid increases, its viscosity decreases. This happens because the fluid particles gain more energy and can move past each other more easily, reducing internal resistance to flow.
Which of the following is a feature of laminar flow?
A High turbulence
B Parallel layers
C Irregular motion
D Variable pressure
Laminar flow is characterized by smooth, parallel layers of fluid moving in an orderly fashion with no mixing between the layers. It is common in low-velocity, high-viscosity fluids and occurs when the Reynolds number is low.
What type of flow occurs when fluid moves in an irregular, chaotic manner?
A Steady flow
B Uniform flow
C Turbulent flow
D Laminar flow
Turbulent flow is characterized by chaotic and irregular motion of fluid. It typically occurs at high velocities and with low-viscosity fluids. The flow is often accompanied by eddies and vortices, and it is less predictable.
In fluid mechanics, which equation describes the conservation of mass in a flow system?
A Continuity equation
B Reynolds equation
C Bernoulli’s equation
D Navier-Stokes equation
The continuity equation is derived from the conservation of mass and states that the mass flow rate in an incompressible fluid is constant throughout the flow. It relates the velocity and cross-sectional area at different points in the pipe.
What is the relationship between Reynolds number and flow regime?
A Inversely proportional
B No effect
C Predicts laminar or turbulent flow
D Directly proportional
The Reynolds number helps predict the flow regime of a fluid. A low Reynolds number (<2000) indicates laminar flow, while a high Reynolds number (>4000) predicts turbulent flow. In between, flow can be transitional.
What is the primary factor affecting the drag force on an object moving through a fluid?
A Object shape
B Fluid color
C Fluid pressure
D Temperature
The drag force is greatly influenced by the shape of the object moving through the fluid. Streamlined shapes experience less drag by allowing smooth fluid flow, whereas blunt shapes cause higher drag due to turbulence and resistance.
What does the term “hydraulic diameter” refer to?
A Pipe radius
B Flow velocity
C Cross-sectional area
D Non-circular ducts
The hydraulic diameter is used for flow calculations in non-circular ducts. It is defined as four times the cross-sectional area divided by the wetted perimeter, providing an effective diameter to simplify the analysis.
How does the flow rate change when a fluid flows through a narrowing pipe?
A Depends on fluid type
B Stays constant
C Decreases
D Increases
According to the continuity equation, the flow rate remains constant in an incompressible fluid regardless of the pipe diameter. As the diameter narrows, the velocity of the fluid increases to maintain the same flow rate.
What causes the formation of vortices in fluid flow?
A Sudden changes in direction
B Low velocity
C High pressure
D Steady flow
Vortices are created when the fluid experiences sudden changes in direction or velocity, causing swirling motion. These regions of rotating fluid are commonly observed around objects moving through a fluid or in turbulent flow.
What is the primary purpose of a pump in a hydraulic system?
A Increase velocity
B Increase temperature
C Decrease flow rate
D Increase pressure
A pump in a hydraulic system is used to increase the pressure of the fluid, enabling it to flow through the system and do work, such as lifting or moving the fluid to another location.
What does the term “streamline” refer to in fluid flow?
A Density variation
B Velocity gradient
C Path of particles
D Direction of pressure
A streamline represents the path that a fluid particle follows in steady flow. The velocity at each point along a streamline is tangent to the streamline. Streamlines help visualize how the fluid is flowing.
What factor does NOT affect the velocity profile of flow in a pipe?
A Pipe color
B Pipe diameter
C Fluid viscosity
D Fluid temperature
The velocity profile in a pipe is influenced by the pipe diameter, fluid viscosity, and temperature, but not by the pipe’s color. These factors determine how the fluid behaves and its velocity distribution across the pipe.
