Balanced forces have the same magnitude but opposite direction. They balance each other, and so cancel each other out. A classic example of balanced forces would be the gravitational force and the normal force acting on an object placed on a horizontal surface. Balanced forces cause no change in the direction or speed of an object.
Unbalanced forces don't have the same magnitude. If an unbalanced force acts on an object, it impacts the object's motion. For example, if something falls, it's because of gravitational force. Air resistance force counteracts gravity, but it doesn't balance it out if the object is too heavy.
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