What is the bearing of a pendulum?
The bearing on a clock pendulum is usually two knife edges with a cross piece balanced upon it supporting the pendulum. Sometimes on cheaper clocks a very thin strip of springy steel is used.
What determines whether a pendulum swings in a plane or describes a three-dimensional path?
A pendulum on a knife edge bearing may swing back and forth in a plane (relative to the Earth). A pendulum suspended from a needle bearing may swing in elliptical fashion on the surface of a sphere. For the movement to stay parallel to a plane which is fixed relative to the stars, the pendulum must have a needle bearing but no initial momentum perpendicular to that plane. However, the origin of that plane will…
What is friction and how does it affect the swing of a pendulum?
Friction is just resistance to movement due to sliding surfaces or to air flow. For a pendulum it will be due to two things: one the resistance in its support bearing, the other to the air resistance of the pendulum itself. Thus energy is gradually lost and the pendulum will eventually come to rest unless it gets a little kick as required, this is supplied in an old clockwork mechanism by the spring which you…