centrifugal or centripetal force

centrifugal force
Centrifugal force (from Latin centrum "center" and fugere "to flee") is a term which may refer to two different forces which are related to rotation. Both of them are oriented away from the axis of rotation, but the object on which they are exerted differs.

光子(photon)
is the elementary particle responsible for electromagnetic phenomena. It mediates electromagnetic interactions and makes up all forms of light. The photon has zero mass and travels at the constant speed c, the speed of light in empty space. However, in the presence of matter, a photon can be absorbed, transferring energy and momentum proportional to its frequency. Like all quanta, the photon has both wave and particle properties, exhibiting wave–particle duality.