Definition of force is obtained from newton's which law
Answers
First law every object ramains constant till any outer force acts on it
The purpose of force has been introduced by first law and the definition has been derived from the same first law.
" Every body continues in its state of rest or of uniform motion along a straight line unless it is compelled by an external force"
The statement helps to define the force as:
The force is defined as the one which changes or tends to change the state of rest or of uniform motion along a straight line.
Also right from the first law we come to know about the concept of inertia of material body.
Inertia is defined as the inability of a material body to change the state of rest or of uniform motion along a straight line on its own.
Of course the second law gives the way to measure that force.
Third law explains about the action-reaction pair.