Explain the primary concept of force.

(N/A) To bring a stationary object into motion,a force is required. Similarly,to slow down an object in motion or to stop a moving object,a force is required.
$A$ ball is moving down along a slope. By applying a force in the opposite direction,it can be stopped. The external parameter (agency) by which the state of motion or rest can be changed is called force.
The effects of force on a body can be the following:
$(i)$ Force can bring a body from rest to motion or a body from motion to rest.
$(ii)$ It can increase or decrease the speed of an object.
$(iii)$ Force can change the direction of motion of an object.
$(iv)$ Force can change the shape of an object.