Volume 21: Pages 85-90, 2008
Relativistic pendulum and the weak equivalence principle
Jaroslav Hynecek 1
1Isetex, Inc., 905 Pampa Drive, Allen, Texas 75013 U.S.A.
This article derives equations for the relativistic proper period of oscillations of a pendulum driven by electrical forces and for a pendulum driven by gravitational forces. The derivations are based on Einstein’s Special Relativity Theory and in particular on the Lorentz coordinate transformation, which has been experimentally verified many times and which is a well-recognized principle for all the modern physics. Since the pendulum proper period of oscillations is an inertial motion invariant, the derived formulas may be used to study the motion dependence of the inertial and gravitational masses. It is found that the well-publicized equivalence between these two masses, which is assumed independent of any inertial motion, cannot be sustained and a new mass equivalence principle must be considered where the equivalence of these two masses holds only at rest.
Keywords: Special Relativity Theory, Inertial Mass, Gravitational Mass, Weak Equivalence Principle, Relativistic Pendulum, Proper Time, Proper Pendulum Oscillation Period, Lorentz Coordinate, Transformation
Received: October 1, 2006; Accepted: March 11, 2008; Published Online: January 15, 2009