A pendulum bob oscillates between potential energy maxima at the top of its swing through kinetic energy maxima at the bottom of its swing. The potential energy is given by the mass times the height of the arc times gravitational acceleration and the kinetic energy maximum is given by the mass times the maximum velocity times the average velocity. Energy may be treated as a scalar in many phenomena, but here both energies are products of two vectors, fall direction and gravitation for potential energy and momentum times average velocity for kinetic energy. This nature of the pendulum is important.
The potential energy of the pendulum is equal to the work it can do under gravitational acceleration until its string is vertical. That work accelerates the pendulum bob to its maximum velocity. The kinetic energy of the pendulum is equal to the work it can do against gravitation to bring the pendulum bob to the top of its arc. It is posited that the shape of the atoms and molecules in the bob is the cause of its acceleration in the refraction gradient of a gravitational field, like a light path bending when passing a star. When the bob is free to move, their asymmetrical oscillations change the position of the bob as the process of falling. The response of the atoms and molecules in the bob to motion is to adjust their shape in order to remain in harmony with themselves, that is they shorten to enable complete oscillations despite translation. These shape changes together transfer potential energy to kinetic energy in the bob which is then available for the work of lifting the bob by reversing the changes in shape while decelerating. The key to this speculation is that reversible refraction or translation compensation actually move the location of internal oscillations in matter.