freefalling

Freefalling refers to the motion of a body under the influence of gravity, with negligible or no contact forces from supporting surfaces. In the idealized sense, free fall occurs in a vacuum where no air resistance acts on the object, so the only force is gravity and the acceleration is constant, about 9.81 m/s^2 near Earth's surface. In the real world, air resistance produces a drag force that increases with velocity, so objects accelerate until the drag force balances weight, reaching terminal velocity. The time profile of free fall thus depends on the object's mass, shape, cross-sectional area, and the density of the surrounding medium.

In physics, the ideal model yields simple relations: velocity v = g t and displacement s = 1/2 g t^2, with downward motion taken as the positive direction in many formulations. When drag is present, the equation of motion becomes m dv/dt = m g − (1/2) ρ C_d A v^2, leading to a terminal velocity where dv/dt = 0. Terminal velocity varies widely: lighter, more streamlined bodies fall faster or slower depending on orientation and surface area, while more streamlined shapes reach higher terminal speeds in air.

Applications and phenomena: The term is central to skydiving, where a period of free fall precedes parachute deployment, with duration and sensation influenced by posture, equipment, and altitude. Free fall is also a fundamental aspect of orbital mechanics: objects in orbit are in continuous free fall around a planet, experiencing microgravity.

Historically, free fall helped establish the law of gravitation and the concept of acceleration due to gravity. Early experiments by Galileo suggested that, neglecting air resistance, all bodies accelerate at the same rate regardless of mass; later, Newton formalized the gravitational framework.