Here's why:
* Terminal velocity is the constant speed that a freely falling object eventually reaches when the force of air resistance equals the force of gravity.
* Acceleration is the rate of change of velocity.
* Since the object is no longer speeding up or slowing down at terminal velocity, its velocity is constant, and therefore its acceleration is zero.
Think of it like this: when a skydiver reaches terminal velocity, they are falling at a constant speed, not accelerating.
