Forces and Motion: Free Fall

The concept of free fall is when any object is subject to gravity only with no resistance. This is an idealised situation that doesn’t occur in real life due to air resistance but it’s a helpful concept to understand in physics.
All objects, regardless of mass, fall at the same rate in a vacuum. This rate is known as the acceleration due to gravity, which is approximately 9.8 m/s^2 on Earth.
In real-world situations, air resistance affects the rate of an object’s fall. The force of air resistance increases as an object’s speed increases, which slows the object down.
Terminal velocity is achieved when the downward force of gravity equals the upward force of air resistance. At terminal velocity, an object falls at a constant speed.
The formula to calculate the distance an object falls in a vacuum is: distance = 0.5 x gravity x time^2.
The formula to calculate the speed of an object in free fall is: speed = gravity x time.
An object in free fall follows a parabolic path when thrown sideways at the same time. This motion, called projectile motion, combines uniform horizontal motion with accelerated (due to gravity) vertical motion.
To solve problems involving free fall, it’s useful to split motion into vertical and horizontal components. Only the vertical motion is affected by gravity and acceleration due to gravity.
Although free fall conditions can’t be achieved on Earth due to air resistance, scientists can create these conditions in a vacuum chamber or in space, which aids the understanding of the principles of motion and forces.
Remember that graphs often provide a good way of understanding and analysing the motion of falling objects. A distance-time graph for a falling object starts off with a gentle slope (low speed), but the slope gets steeper as time goes on due to the continuous increase in speed resulting from the constant acceleration of gravity.
A speed-time graph for a free-falling object is a straight line, showing that the acceleration (the gradient of the line) is constant.