I cannot understand the the relation between Reynolds Transport Theorem and Volume Calculation. Volume calculation is an simple, straightforward process which, I think, have much connection between Reynolds Transport Theorem. We calculate volumes in thermodynamics, heat transfer and fluid mechanics. So I would like to ask why this problem is given under RTT. View attachment 197658 Source: A Brief Introduction to Fluid Mechnanics by Munson/Young/Okiishi/Huebsch. Thank you.