Inertia

An object in motion may be in motion due to each an unbalanced force or a balanced force. In the scenario of a balanced force gravity most likely does not apply. The only forced exerted on an object are those of the initial push. A balanced force within the bounds of Earth is highly unlikely. On the other hand unbalanced forces present themselves constantly. An unbalanced force has opposing forces acting upon an object, however the forces do not equal. This is what causes the change in velocity and the acceleration. In our case the Ping-Pong ball is being hit across the table. This scenario is a depiction of projectile motion; a type of motion with categorizes itself under unbalanced forces. The strike of the Ping-Pong racquet causes an imbalance between forces. Since the hit of the racquet has a bigger magnitude then air resistance it sends the ball into motion. This motion is caused by the change in velocity (acceleration) and is a direct resultant of the imbalance of forces.

 

V ≠ 0

A = 0    or    A ≠ 0

ΣF = 0   or   ΣF≠ o