A gas flows along the \(x\) axis with a speed of \(V=5 x \mathrm{~m} / \mathrm{s}\) and a pressure of \(p=10 x^{2} \mathrm{~N} / \mathrm{m}^{2}\), 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.