Resultant Forces

Resultant force = overall force on a point or object

At least 2 forces acting on an object, the overall effect of these forces decide the motion of the object (accelerate, decelerate or steady speed)

number of forces acting at a single point you can replace them with a single force, if forces act along the same line, the overall effect is found by adding or subtracting them...the overall force = resultant force 

A resultant force = change in velocity, if there is a resultant force acting on an object, the object will change its state of rest or motion, it causes a change in the objects velocity.