A 2-kg object is dropped from a height of 1000 m. What is the force of air resistance on the object when it reaches terminal velocity?
The falling object experiences its weight acting downwards and the air resistance in the opposite direction.
The air resistance increases with velocity so there may come a point, depending on the shape of the object and if there is sufficient height, where these 2 forces are equal.
Since the object has no net forces acting on it it will, according to Newton, no longer accelerate but continue with a constant velocity.
This is called Terminal Velocity.
Air resistance = weight
In the graphic you can see that the large air resistance of the parachute is balanced by her weight. She floats to the ground at a constant, terminal, velocity.