Terminal Velocity

When an object falls through a fluid (air or liquid):

1. Initially, weight is greater than drag, so the object accelerates downward.
2. As speed increases, drag increases.
3. Eventually drag equals weight, so the resultant force is zero.
4. With zero resultant force, the object moves at constant velocity: terminal velocity.

Factors affecting terminal velocity: mass (heavier = faster), surface area (larger area = slower), shape (streamlined = faster), fluid density (denser fluid = slower).

Skydivers reach about 55 m/s (body flat) or 90 m/s (head first). Opening a parachute greatly increases the surface area, reducing the terminal velocity to about 5 m/s.