I'll take the sky diver example. Right when a sky diver jumps out of the plane the net force of the diver is greatest. Then the diver begins to reach terminal velocity where the force of resistance = the force of gravity. So while the force of air resistance increases to equal the force of gravity is the sky diver decelerating?
[Physics] Does an object decelerate when reaching terminal velocity
newtonian-gravitynewtonian-mechanics
Best Answer
No, it ceases to accellerate.
Consider $F = ma$. You say because $F_r = -F_g$, net $F$ is zero. What does that imply about $a$?