1. Force is one of the basic concepts in mechanics, which is the fundamental reason for changing the motion state or deformation of objects.
 2. Force is generated by the interaction between objects. The size, direction and action point of force are the three elements of force; It can also be defined as the rate of change of momentum to time.
 3. In dynamics, force is equal to the product of mass and acceleration of an object.
 4. Force is the action of an object on an object and cannot exist alone without an object.
 5. A force may also be generated between two objects that are not in contact.
 6. The forces act on each other.
 7. The international unit of force is Newton, or cattle for short, and the symbol is N. This is named in memory of the British scientist Isaac Newton.
 8. Common measuring tools of force include spring scale, dynamometer, etc.