NAM logo, by David Le Conte

Dynamics Newton knew and we don't

D. Lynden-Bell (IoA, Cambridge)

Newton showed that if with respect to some point S a body in orbit swept out equal ares in equal times then the force on that body was central to S. But if the orbit was not in a plane through S then the central force was supplemented by a force perpendicular to both the radius from S to it and the velocity. Such forces preserve the scalar magnitude of the angular momentum but not the individual components.

We study what forces conserve the magnitudes of other vector constants of the motion without conserving the components of them.

Maintained by Ian Howarth