Free fall is the motion of a body where gravity is the only force acting upon it. In classical mechanics, an object is said to be in free fall if it moves solely under the influence of gravity, without any other forces such as air resistance or lift acting on it
. Key points about free fall:
- The acceleration of a free falling object near Earth's surface is constant and equal to the acceleration due to gravity, approximately 9.8 m/s² downward
- Free fall is not limited to objects falling downward; an object moving upward or orbiting (like the Moon or a spacecraft) can also be in free fall if gravity is the only force acting on it
- In free fall, all objects accelerate at the same rate regardless of their mass or shape, as demonstrated by Galileo's experiments
- The sensation of weightlessness occurs in free fall because there is no normal force acting on the body, such as when astronauts orbit Earth in a spacecraft
- When air resistance or other forces act on the object (like a parachute or aerodynamic drag), the motion is no longer considered true free fall in the strict physics sense
Mathematically, the velocity and position of a free falling object can be described by the equations:
- v(t)=v0−gtv(t)=v_0-gtv(t)=v0−gt
- y(t)=y0+v0t−12gt2y(t)=y_0+v_0t-\frac{1}{2}gt^2y(t)=y0+v0t−21gt2
where ggg is the acceleration due to gravity, v0v_0v0 is the initial velocity, and y0y_0y0 is the initial height
. In summary, free fall is the motion of an object influenced only by gravity, resulting in a constant downward acceleration and the experience of weightlessness if no other forces interfere.
