Physics
Newton’s (three) Laws of Motion
Sir Isaac Newton used the concept of force to describe the motion of a particle by three laws. These laws are valid when the velocity of the particle does not approach the speed of light and the size of the particle does not go down to the atomic level – they lie in the domain of classical mechanics.
Electric charges, force and field
There are two kinds of electric charges – positive and negative. A charged object sets up an electric field in its surrounding space and exerts an electric force on another charged object that enters this field.