# Tutor profile: Michael S.

## Questions

### Subject: Physics (Fluid Mechanics)

Why is total pressure not the same value on either side of a shock wave but total temperature is?

Total pressure changes due to the fact that that a shock is a non-isentropic event (i.e. entropy is not constant) and therefore the actual chemical properties of the fluid are affected. Enthalpy, however, is not affected as there is no work done on the fluid by the wave, and so no heat energy is added or "removed" from the fluid, and therefore total temperature is the same.

### Subject: Calculus

What is the relationship between derivatives and limits?

A derivative is just a limit (i.e. a finite difference) as the difference term of the limit approaches 0; the difference between the two terms becomes infinitesimally small. This is an analytical approach to the same idea used by geometric methods of approximation.

### Subject: Aerospace Engineering

Why is total pressure not the same value on either side of a shock wave but total temperature is?

Total pressure changes due to the fact that that a shock is a non-isentropic event (i.e. entropy is not constant) and therefore the actual chemical properties of the fluid are affected. Enthalpy, however, is not affected as there is no work done on the fluid by the wave, and so no heat energy is added or "removed" from the fluid, and therefore total temperature is the same.

## Contact tutor

needs and Michael will reply soon.