Terminal velocity is reached under what conditions?

• A. Drag force is less than weight and acceleration is zero.
• B. Drag force equals weight, net force zero, acceleration becomes zero.
• C. Drag force equals weight but acceleration continues to increase.
• D. Only occurs in vacuum.

Answer: (B)

Terminal velocity happens when the upward drag force from air exactly balances the downward weight of the falling object. As you fall, speed increases, and so does drag. When drag equals weight, the net force is zero, so acceleration is zero and the velocity becomes constant. That constant speed is the terminal velocity.

So the best answer is the one that says drag equals weight, net force is zero, and acceleration is zero. If drag were still less than weight, there would be a net downward force and the object would keep speeding up, not at terminal velocity. If drag equal weight but acceleration somehow kept increasing, that would contradict the idea that zero net force means zero acceleration. In a vacuum there’s no air, so no drag to balance weight, so terminal velocity can’t be reached.