I have been playing around with the physics engine, but haven’t been able to figure out how to make physics apply to one part of an animation but not to the other.
For example, I’d like to have a ball on a pendulum (a ball attached to a rod that’s fixed at the top) swinging freely according to the laws of physics (decelerating at the top, maybe with some friction, etc.), but at time T, have the ball fall off the rod, and go in some random direction, not the direction it’s supposed to go according to Newtonian physics.
When you set up an object to use Rigid Body settings, look in the setting panel under the dropdown menu where you select Active or Passive. There’s a checkbox labeled “Dynamic.” Make sure it’s checked, then add a keyframe to it on frame 1 (right click the checkbox, Insert Keyframe). Now go to the frame where you want it to start behaving oddly. Uncheck it and insert another keyframe. Beginning with that frame, it will stop being affected by rigid body physics. You can now keyframe its motion to go wherever you like.