At terminal velocity, which forces balance?

• A. Drag force equals weight.
• B. Normal force equals gravitational force.
• C. Friction equals acceleration.
• D. Buoyant force equals weight.

Answer: (A)

When an object falls through air, it keeps accelerating until the upward drag force becomes strong enough to counteract the downward weight. At that moment the net force is zero, so there’s no further acceleration and the speed stays constant—that constant speed is terminal velocity. The drag force opposes the motion, and gravity pulls downward, so they balance when terminal velocity is reached.

Normal force only exists when you’re in contact with a surface, so it doesn’t apply to free-falling objects. Friction isn’t a direct driver of motion here in the way that would tie it to acceleration. Buoyant force does act upward, but in basic terms the condition most people learn is drag balancing weight; if buoyancy is considered, you’d say drag balances the weight minus buoyant force, which is a more precise accounting but is often neglected in simple problems.