Force Vector Field of the Restricted 3body system
The "restricted 3body problem"
involves 5 Lagrange points in the system of two orbiting primary
masses. The Lagrange points are unstable equilibrium points for
motionless masses (masses not moving relative to the rotating frame of
the two primaries).
The effect of the gravitational
attractions of the two primaries, as well as the noninertial forces
created by observing the system from within the moving frame, creates
a net force inside this frame that relates to the position of any
third small mass. The physlet to the right is used to illustrate that
force by creating a "vector field" showing the strength (via
the colors of the arrows) and the direction of the forces at points in
the "grid" of the plane.
You can use the radio buttons
below to select different systems to watch (different pairs of
gravitational objects), as well as different areas of the rotating
plane to watch  so you can zoom in and see the vector field more
closely near the Lagrange points.
