Gravitation Inside Earth

1
Gravitation Inside Earth
A uniform shell of matter exerts no net
gravitational force on a particle located inside
it. This means that the sum of the force vectors
on the particle from all the elements is zero.
Uniform Earth
Real (nonuniform) Earth
The force on the particle actually increases as
the particle begins to descend. The force reaches
a maximum at a certain depth and then decreases
as the particle descends farther.
2
Gravitational Potential Energy
In Section 8-4, we discussed the gravitational
potential energy of a particleEarth system. We
were careful to keep the particle near Earths
surface, so that we could regard the
gravitational force as constant. We then chose
some reference configuration of the system as
having a gravitational potential energy of zero.
Often, in this configuration the particle was on
Earths surface.