Welcome to Chafia physic. In this post i just want to share with you about, What is terminal velocity and how it reached . Fisrt lets start about what is definition of teminal velocity. Terminal velocity is a maximum velocity that a thing (example: a ball) can reached when it moves inside a fluid (example: air, water, oil, etc). The reason why this maximum velocity comes up is a force that called Drag Force , where it force has opposite direction with the movement. This opposite force in one situation will make the total force to be zero, and make the ball moves in constant velocity. To get more understanding with this situation let's we take a look with example below. Problem: A ball with mass m=0.01 kg and radius R=0.05m falling from the rooftop 120 m from street without initial velocity. If the density of Air is 1.2 kg/m^3 and the Drag coefficient is 0.5 (for sphere) Find terminal velocity of this ball. And compare with the velocity of ball before hit the street if the drag...