Test Chapter 1 - Fluids: definition, properties and basic notion

Fluids are different from solids mainly because:

• They can be considered continuous media
• They are highly compressible
• They deform without arriving to an equilibrium
• a) and b) are true

The high compressibility of gases is due to:

• Their low molecular density
• Their high molecular stability
• Their high molecular density
• They are fluid media

The no-slip condition is originated mainly because:

• The effect of the surface roughness
• The fluids are continuous media
• The thermodynamic equilibrium
• The high value of the Knudsen’s number

The “bar” unit for pressure:

• Is the base unit in SI
• Is the base unit in the cgs system
• Is based in the standard conditions at 0 ºC
• Is just a multiple of Pa

If the atmospheric pressure is the standard 1 Atm, and a manometer measures a relative pressure of -2 Bar, the absolute pressure is:

• -1 Bar
• -98675 Pa
• 0 Pa
• The manometer is broken

The force exerted by the pressure over a surface

• Is always vertical
• Is always perpendicular to the surface
• Its direction depends on the shear stress
• Is coplanar to the surface

Which value is not similar?

• 1 atm
• 1 Bar
• 1 GPa
• 1 Kg/cm2

A liquid at ambient temperature can boil if:

• The relative pressure is negative
• The pressure is lower than the vapor pressure
• The pressure is higher than the vapor pressure
• It can’t boil at ambient temperature

In the state equation for perfect gases,

• The pressure can be relative if the temperature is in ºC
• The temperature can be relative if R is in ºC
• The pressure has to be absolute
• The pressure can be relative but always expressed in Pa

The sound propagation speed of a perfect gas:

• Depends on the temperature
• Depends on the pressure
• Depends on the density
• Is constant