Disable physics between certain meshes?

Hello,

How would I get about disabling physics between certain meshes. For instance, If I have a static sphere parented to a cube with rigid body physics, when the sphere intersects the cube, the cube freaks out and flies all over the place. Here is a pic to explain the situation a little better


. So how can I disable physics between the sphere and cube but enable physics between the sphere and other objects? I hope I explained my situation clearly.

Thanks!

sensor object, or 6dof joints or collision layers/masks

Thank you!