What phenomenon describes a spinning object traveling through a viscous fluid applying a force perpendicular to its velocity?

The Magnus effect refers to the phenomenon where a spinning object moving through a fluid, such as air or water, experiences a force that is perpendicular to both its direction of motion and the axis of its spin. This occurs because the rotation of the object alters the pressure distribution around it, creating a difference in pressure that generates lift or a side force.

As the object spins, the fluid moves faster on one side of the object, reducing the pressure in that area, while the fluid flows slower on the opposite side, resulting in higher pressure. The net result is that the object is pushed toward the lower-pressure side, creating a lateral motion that can significantly affect the trajectory of the object.

In aviation, this effect is crucial for understanding how control surfaces like ailerons and rudders work, as well as how balls in sports like soccer and baseball curve through the air. Therefore, the Magnus effect is accurately described by the conditions of the question, marking it as the correct answer.