in which x is shorthand for all the phase space coordinates.
2c. Special cases for the equations of change
We now make special choices for B so that we will get the familiar equations of change:
B at position r
To get the mass density at position r, we have to require the masses of the various beads to be located at r, and this is accomplished by means of the delta function in Eq. 2.9. Similar comments may be made for the computation of the momentum density, the energy density, and the angular momentum density.
By the first choice of B above (in Eq. 2.9) we get the equation of continuity for species :