Newton originated his 2 nd law in a different form than we u
     Newton originated his 2 ^nd law in a different form than we usually express it in terms of acceleration. In his original form, force is determined by the time rate of change of   
  
  Solution
Momentum
The second law states that the net force on an object is equal to the rate of change (that is, the derivative) of its linear momentum p in an inertial reference frame.
NOTE: Just for added information:
Newton\'s original Latin reads: \"Lex II: Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum lineam rectam qua vis illa imprimitur\"
According to modern ideas of how Newton was using his terminology, this is understood, in modern terms, as an equivalent of: \"The change of momentum of a body is proportional to the impulse impressed on the body, and happens along the straight line on which that impulse is impressed\"

