Hello, I have got an question. How can I calculate the velocity of an object which I'll drop from a height of 1 meters with a starting velocity of 0 m/s? I did some research myself and found out that I can calculate this with using the following formula: St = 0.5 * 9.81 * t^2 St = distance t = time in seconds So: t^2 = 1 / 0.5 * 9.81 = 0.20 -> t = 0.45 sec Velocity after 1 meter: v = 9.81 * t -> 9.81 * 0,45 = 4.42 m/s However, I understand that this is in a vacuum. But I want to know the real velocity in air. Therefore I need to know more about the shape and area of the object and the density of air. Which are: Shape: half-sphere Diameter: 2 cm Mass of the object: 0.2 kg Area: 0.0006 m^2 Density of air: 1.293 kg*m-3 However, I also found a drag coefficient at: http://en.wikipedia.org/wiki/Drag_coefficient" [Broken] which is 0.42 I would like to know if I'm right with what I wrote above. How do I calculate the velocity of the object after 1 meters? Can I use the drag coefficient above and how? Or does the coefficient depend too much on the area of the object? Can someone give me an example how I can calculate this?