Force

In physics force means any influence that causes a Free body to undergo in an acceleration. In other words it is a push or pull that can cause an object with mass to change its velocity. A force has both magnitude and direction which make it vector quantity. Newton's second law, F=ma, can be formulated to state that an object with a constant mass will accelerate in proportion to the net force acting upon and in inverse proportion to its mass, an approximation which breaks down near the speed of light. His original formulation is exact , and does not break down: this version states that the net force acting upon an object is equal to the rate at which its momentum changes.

In short force is an external agent .

Related concepts to accelerating forces include thrust, increasing the velocity of the object, drag, decreasing the velocity of any object, and torgue, causing changes in rotational speed about an axis. Forces which do not act uniformly on all parts of a body will also cause mechanical stress , a technical term for influences which cause deformation of matter. while mechanical stress can remain in solid object, gradually deforming it. thrust is a force which act upon body in opposite direction. It means that it can also called as pseudo force.