Hydraulics and Fluid Power Systems (MECH) test-1

Which property of a fluid is defined as its resistance to deformation or flow?

• Density

• Viscosity

• Surface tension

• Specific weight

Answer explanation

Viscosity is the property of a fluid that measures its resistance to deformation or flow. It indicates how thick or sticky a fluid is, making it the correct choice compared to density, surface tension, and specific weight.

The unit of dynamic viscosity in SI is:

• N·s/m²

• Pascal

• Poise

• m²/s

Answer explanation

The unit of dynamic viscosity in SI is expressed as N·s/m², which represents Newton-seconds per square meter. This is the correct choice, as Pascal (Pa) is a unit of pressure, and Poise is a CGS unit.

A fluid is said to be ideal if it has:

• No viscosity

• Incompressibility

• Both a and b

• None of the above

Answer explanation

An ideal fluid is characterized by having no viscosity (it flows without resistance) and being incompressible (its density remains constant). Therefore, the correct answer is both a and b.

The pressure at a point in a fluid at rest is called:

• Absolute pressure

• Atmospheric pressure

• Gauge pressure

• Hydrostatic pressure

Answer explanation

The pressure at a point in a fluid at rest is known as hydrostatic pressure. It is the pressure exerted by the weight of the fluid above that point, distinguishing it from absolute, atmospheric, and gauge pressures.

Pascal’s law is applied in:

• Hydraulic lifts

• Centrifugal pumps

• Flow through pipes

• Jet turbines

Answer explanation

Pascal’s law states that pressure applied to a confined fluid is transmitted undiminished in all directions. This principle is utilized in hydraulic lifts, allowing them to lift heavy loads efficiently.

4. The pressure variation in a fluid column is directly proportional to:

• 4. Depth of the fluid

• 4. Viscosity of the fluid

• 4. Surface tension of the fluid

• 4. Volume of the fluid

Answer explanation

The pressure variation in a fluid column is directly proportional to the depth of the fluid due to the weight of the fluid above. As depth increases, the pressure increases linearly.

The continuity equation is derived from the principle of:

• Conservation of momentum

• Conservation of mass

• Conservation of energy

• None of the above

Answer explanation

The continuity equation is based on the conservation of mass, which states that mass cannot be created or destroyed in a closed system. This principle ensures that the mass flow rate remains constant in fluid dynamics.

Bernoulli’s equation is applicable to:

• Steady, incompressible flow

• Unsteady, compressible flow

• Viscous fluid flow

• None of the above

Answer explanation

Bernoulli’s equation applies to steady, incompressible flow, where the fluid's density remains constant and the flow characteristics do not change over time. Other options do not meet these criteria.

Streamlines represent:

• Constant velocity paths

• Constant pressure paths

• Constant density paths

• Constant flow rate paths

Answer explanation

Streamlines represent constant velocity paths in a fluid flow. They indicate the direction and speed of the fluid at every point, showing how particles move through the flow without changing speed.

In laminar flow through a pipe, the velocity distribution is:

• Parabolic

• Linear

• Uniform

• None of the above

Answer explanation

In laminar flow through a pipe, the velocity distribution is parabolic due to the effects of viscosity, where the fluid moves slower near the pipe walls and faster in the center, creating a parabolic profile.