Understanding Terminal Velocity: Why Falling Objects Don’t Speed Up Forever

When you drop an object, it doesn’t just keep accelerating endlessly. Instead, it eventually reaches a maximum speed, a speed beyond which it cannot fall any faster. This ultimate limit is known as terminal velocity. To understand why this happens, let’s break down the forces at play during a free fall.

Free Fall: When an object is falling, the two main forces acting on it are weight and air resistance

Free Fall: The Two Forces That Matter

1. Weight The weight of the object remains constant throughout the fall. The weight of the object is the force due to the mass being acted on by Earth’s gravity.
2. Drag (Air Resistance) Air resistance is a frictional force that acts against the movement of an object. However, if an object is falling in a vacuum, there is no air resistance. As an object falls, it initially accelerates. The faster the object is travelling, the greater the air resistance acting against it.

Terminal Velocity:

Terminal velocity is the highest speed an object can reach when falling through a fluid (like air or water).

It occurs when:

The downward pull of gravity = The upward push of air resistance

Imagine sticking your hand out of a moving car window. You immediately feel a strong push of air that’s drag. The faster the car goes, the stronger this push feels.

Falling works the same way:

• As you fall faster, drag increases.
• Eventually, drag becomes large enough to balance your weight.
• This is Terminal velocity, the maximum falling speed.