i hope we will not be cooked

When an object travels faster than the local speed of sound, a shock forms because

Disturbances cannot travel upstream

In an ideal gas, the speed of sound depends on

Temperature and specific heat ratio

The total-to-static pressure ratio after a normal shock is lower than before primarily due to

Irreversibility in the shock process

If flow upstream of a normal shock is subsonic, the shock will

Not be physically possible

A Pitot tube in supersonic flow before and after a normal shock will read

Higher total pressure upstream of the shock

What is the significance of total temperature in a normal shock analysis?

It remains constant across the shock

In an expansion fan, the streamlines

Spread smoothly and turn away from each other

What makes a Prandtl-Meyer expansion isentropic?

Each wave in the fan behaves as an infinitesimally weak disturbance

Which of the following best describes a Mach wave?

The limiting case of an infinitesimally weak oblique shock

How is information propagated in supersonic flow that leads to shock formation?

Via molecular collisions that fail to move upstream

In a steady, inviscid, adiabatic flow, which quantity is constant along a streamline?

Total enthalpy

What does the total temperature represent in a compressible flow?

Temperature when brought to rest adiabatically

Which assumption must be added to adiabatic flow to define total pressure?

Reversible

Total pressure in a compressible flow

Remains constant for isentropic flow

Why does a normal shock wave result in an increase in entropy?

The process is non-isentropic and involves internal dissipation

What distinguishes isentropic flow from merely adiabatic flow?

Absence of dissipative effects

Which condition justifies the assumption of isentropic flow over most of an airfoil?

Thin boundary layers outside which viscous effects are negligible

What is the main reason pressure increases drastically across a normal shock?

Kinetic energy is transformed into internal energy

Which quantity does a Pitot tube measure in compressible flow?

Total pressure

Why is the flow behind a normal shock always subsonic?

The deceleration causes the Mach number to drop below unity

Which thermodynamic quantity does not change across a normal shock?

Total enthalpy

Which of the following best describes the transformation across a normal shock?

Kinetic energy to internal energy

In the derivation of shock equations, which effects are neglected?

The control volume isolates one direction

What happens if two left-running shock waves intersect?

A stronger shock continues

What makes a normal shock different from a sound wave?

Shocks cause finite changes in properties, sound waves involve infinitesimal changes

What causes an oblique shock to form when a supersonic flow encounters a concave corner?

Flow is turned into itself, requiring a pressure adjustment

Why can one-dimensional flow equations be used to analyze changes across an oblique shock?

Only the normal component of velocity governs property changes

What flow parameter ensures the formation of an attached oblique shock on a wedge?

The wedge angle must be less than the maximum deflection angle

Why does entropy increase across a shock?

Due to irreversible compression

A process that is adiabatic and has increasing entropy is

Irreversible

Which of the following best explains the meaning of total temperature in compressible flow analysis?

The temperature a gas would reach if decelerated to rest adiabatically

In a wind tunnel with a standing normal shock, which statement is accurate about flow past the shock?

It decelerates from supersonic to subsonic

Why is the velocity in region 2 always lower than region 1 across a normal shock?

Part of the kinetic energy is converted into internal energy

How thick is the region across a normal shock?

Extremely thin, typically molecular in scale

The deflection angle in an oblique shock scenario is

The angle by which the flow is turned due to a surface

Why is there a maximum deflection angle for a given upstream Mach number?

Beyond that angle, no attached oblique shock solution exists

Why is the Mach number a useful criterion for compressibility?

It relates flow velocity to sound speed