cen·trip·e·tal force
noun/ˌsentrɪˌpiːtl ˈfɔːs/, /senˌtrɪpɪtl ˈfɔːs/
/senˌtrɪpɪtl ˈfɔːrs/
(physics)- a force that acts on an object moving in a circle and that is directed towards the centre of the circle
向心力：作用在圆周上运动的物体上并指向圆周中心的力，