Define resultant force as the single force that has the same effect as all the forces acting on an object.

The resultant force is defined as the single force that has the same effect as all the individual forces acting on an object. When multiple forces are applied, they can either add together or cancel each other out, depending on their directions. If the forces are in the same direction, they combine to create a larger resultant force. Conversely, if they are in opposite directions, the resultant force is the difference between the two. Understanding resultant forces is crucial for predicting how an object will move, as a non-zero resultant force will cause acceleration, while a zero resultant force indicates that the object remains at rest or moves at a constant velocity.