Balanced and unbalanced forces

Net force-The amount of force that is making an object change direction or motion

Zero net force-balanced
Not zero-unbalanced (example-40N against 40 N)

Acceleration occurs when an unbalanced net force acts on an object

Friction-the force resisting the relative motion of solid surfaces (example-rubbing your hands together)

Velocity-The rate of change of the position of an object.It is also known as speed.