College Physics Question: How much energy does it take to completely tear the earth apart? The result only contains g, m, r, urgent,
The gravitational potential energy between a sphere with radius r and a spherical shell with thickness dr is
-g*m^2/(4/3 π*r^3)^2 * 4/3 π*r^3 * 4 π*r^2*dr/r
= - 3 G*M^2 / R^6 * r^4*dr
3gm 2/(5r) for integration