Which of the following best describes the role of external forces in movement?

External forces play a critical role in influencing the motion of an object or an organism. They encompass forces that come from outside the body, such as gravity, friction, air resistance, and applied force. When these external forces act on a body, they can cause changes in motion, which may involve alterations in velocity, direction, and acceleration.

For instance, when a person pushes an object, the force exerted causes the object to accelerate. Similarly, when running, gravity acts as an external force that affects how the body moves in relation to the ground. Therefore, the ability of external forces to change an object's state of motion is fundamental to understanding movement dynamics in biomechanics.

This understanding underpins concepts like Newton's laws of motion, where the interplay between internal and external forces dictates the behavior of moving bodies. Recognizing that external forces can indeed change motion helps us appreciate their crucial role in various physical activities, from sports to rehabilitation.