Newton's first law: when there is no external force acting on all objects, they always keep a uniform linear motion or a static state. All objects always keep moving in a straight line at a uniform speed or at rest until an external force forces them to change this state. (Mathematical expressions are difficult to express)

Newton's second law: 1. Law content: the acceleration of an object is directly proportional to the external force F that the object is subjected to, and inversely proportional to the mass of the object. The direction of acceleration is the same as that of external force. 2. Formula: F =ma

Newton's Third Law (Law of Reaction): The action and reaction between two objects are always equal in magnitude and opposite in direction, and act on a straight line. It is expressed as F=-F'