At terminal velocity, which two forces are equal in magnitude?

At terminal velocity, an object moves at a constant speed while falling through a fluid, such as air. This phenomenon occurs when the forces acting on the object balance each other out. In this case, the two forces that are equal in magnitude are the force of gravity, which pulls the object downward, and the force of air resistance (often referred to as drag), which opposes the downward motion of the object.

When an object first starts to fall, gravity accelerates it downwards. As the velocity of the falling object increases, the air resistance also increases until it equals the force of gravity. At this point, the net force acting on the object becomes zero, meaning the object no longer accelerates and continues to fall at a steady speed—this is known as terminal velocity. Thus, the correct answer highlights the balance between the gravitational force and air resistance during this phase of motion.