UNIT 3 - UNDERSTANDING AIR

When an object moves through a fluid, which of the following will affect fluid friction? Select all that apply.

• The fluid’s color

• The fluid’s viscosity

• The speed of the object

• The object’s density

• The shape of the object

An airfoil’s movement through air is similar to _______.

• a moving freight train

• a boat’s movement on water

• a beam of light

• electron flow through a wire

Water has greater viscosity than air.

• True

• False

What is the difference between viscosity and fluid friction?

• Viscosity is a measure of a fluid's resistance to flow, while fluid friction is the resistance between layers of fluid.

• Viscosity is the resistance between layers of fluid, while fluid friction is a measure of a fluid's resistance to flow.

• Viscosity and fluid friction are the same and can be used interchangeably.

• Viscosity is only applicable to gases, while fluid friction is only applicable to liquids.

The Coanda Effect is the tendency of a stream of fluid to _______.

• avoid a moving object

• move below an airplane’s wing

• attach to a convex surface

• go around a wing or rotor

Which of the following are factors that affect air density? Select all that apply.

• Humidity

• Pressure

• Viscosity

• Friction

• Temperature

Millibars (mb) is a unit of measurement for _______.

• air temperature

• density

• atmospheric pressure

• fluid friction

Two substances with the same volume can have different densities because:

• They have different masses.

• They have different colors.

• They have the same mass.

• They occupy different spaces.

Air density increases as altitude increases.

• True

• False

Which of the following statements about air density are true? Select all that apply.

• Air density and air pressure are inversely proportional.

• As temperature increases, so too does density.

• Temperature is inversely related to air density.

• Humid air is less dense than dry air.