Question

ques

Answer 1

This is a volume element of in an imcompressible fluid flowing at a distance x,y,z from the respective axes
In the book it is given coordinates of P as x,y,z but shouldn't they be (x+dx),(y+dy),(z+dz) or (dx),(dy),(dz) if we consider the element at origin
Let
\[\vec V=V_{x}\hat i+V_{y}\hat j+V_{z}\hat k\]
be the velocity of fluid at a point P(x,y,z)
Mass of fluid flowing through face ABCD in unit time is
\[=V_{x}(dy.dz)\]
Now the problem is right in starting, this equation is dimensionally incorrect, the left side is having a unit of mass but right side is jut made up of velocity and length elements