A gas flows along the x axis with a speed of v = 5x m/s and a presure of p = 10x^2 N/m^2, where x is in meters.
a) Determine the time rate of change of pressure at the fixed location x = 1.
b) Determine the time rate of change of pressure for a fluid particle flowing past x = 1.
c) Explain without using any equations why the answers to parts a and b are different.