What do you call opposite directional forces that are equal in magnitude and parallel?

The correct answer, describing opposite directional forces that are equal in magnitude and parallel, is a couple. In mechanics, a couple consists of two equal and opposite forces whose lines of action do not coincide; therefore, they create a rotational effect without translating the object. This unique configuration leads to pure rotation, as the torque produced by the forces acts on a specific axis.

Understanding the concept of a couple is crucial in areas such as machine design and structural analysis because it plays a key role in evaluating the stability and rotation of systems. In contrast, while the terms used in the other options refer to different concepts, they do not capture the essence of forces that cause rotation without translation. Non coplanar refers to forces acting in different planes, which does not apply here as both forces are considered parallel and equal. Centro does not relate to the description of forces and is not a standard term used in mechanics. Coplanar implies forces acting in the same plane but does not specifically address the characteristics of a couple, which focuses on equal, opposite forces creating rotation.