Find the terminal velocity of a falling object — the constant speed reached when air drag balances gravity — using v = √(2mg / ρ·A·C_d).
As an object falls, air resistance grows with speed until it exactly cancels gravity. At that point the net force is zero and the object stops accelerating — it has reached terminal velocity, v = √(2mg / ρ·A·C_d).
Heavier or more compact objects (small area, low drag coefficient) fall faster; thinner air (high altitude) raises terminal velocity. The drag coefficient C_d depends on shape — roughly 0.47 for a sphere and near 1.0 for a spread-eagled skydiver.
It is the constant maximum speed a falling object reaches when the upward drag force equals the downward force of gravity, so acceleration becomes zero.
About 53 m/s (195 km/h) belly-to-earth, or up to ~90 m/s in a head-down dive. It depends on body position, which changes area and drag.
Use v = √(2mg / ρACd), where m is mass, g gravity, ρ air density, A cross-sectional area and Cd the drag coefficient.
Yes, for the same shape and area. Terminal velocity rises with the square root of mass, which is why a heavy object falls faster than a light one of identical size in air.