Stuck on Problem: Need Help Understanding P & Equation

[LCSphysicist]

Homework Statement

Find the proper potential energy of gravitational interac-
tion of matter forming
(a) a thin uniform spherical layer of mass m and radius R;
(b) a uniform sphere of mass m and radius R

Relevant Equations

u = dm*p/2

Actually, i don't even started the solution because i am confused, i am not sure what the question is asking, i tried to see the solution, but it was using

, i don't know what that equation mean. Can you help me? P is like potential electricity, for gravitational force?

 

[PeroK]

I think the question is:

Imagine a shell or sphere forming from particles that start far away from each other. The potential energy of the initial configuration is taken to be zero. What is the potential energy of the final configuration?

 

[Orodruin]

Homework Statement:: Find the proper potential energy of gravitational interac-
tion of matter forming
(a) a thin uniform spherical layer of mass m and radius R;
(b) a uniform sphere of mass m and radius R
Relevant Equations:: u = dm*p/2

Actually, i don't even started the solution because i am confused, i am not sure what the question is asking, i tried to see the solution, but it was using View attachment 262916, i don't know what that equation mean. Can you help me? P is like potential electricity, for gravitational force?

It is not p, it is the Greek letter $\varphi$. It represents the gravitational potential such that $\vec g = - \nabla \varphi$, where $\vec g$ is the gravitational acceleration.