Terminal Velocity

NGScienceX High school education series (ages 13+) Booklet 3 – Terminal Velocity ngsciencex.com What really happens when a skydiver jumps out of a plane? Why don’t they keep speeding up forever? In this video, we break down the physics of terminal velocity in a clear, visual, and intuitive way. The moment a skydiver steps out of an aircraft high above the ground, gravity immediately pulls them downward. Gravity is a constant force, acting on the skydiver the entire time, causing them to accelerate toward Earth. At the very beginning of the fall, gravity is the dominant force, so the skydiver speeds up rapidly. Each second, they are moving faster than the second before. But the story doesn’t end there. As the skydiver gains speed, they begin to collide with more and more air molecules. These collisions create a force known as air resistance (also called drag). Air resistance acts in the opposite direction to motion, pushing upward while the skydiver moves downward. At low speeds, this force is small, but as speed increases, air resistance becomes stronger and stronger. Eventually, air resistance grows large enough to significantly reduce the skydiver’s acceleration. Gravity is still pulling downward, but now it is partially balanced by the upward push of air resistance. The net force on the skydiver becomes smaller, so their acceleration slows. At a certain point, the upward force of air resistance becomes exactly equal to the downward force of gravity. When this happens, the forces are balanced. With no net force acting on the skydiver, acceleration stops. The skydiver is still falling—but now at a constant speed. This constant maximum speed is called terminal velocity. Terminal velocity does not mean the skydiver has stopped falling. It means they are no longer speeding up. They continue to move downward at the same speed for the rest of the fall, unless something changes to alter the forces acting on them. One of the most important factors affecting terminal velocity is body position. When a skydiver spreads out their arms and legs, they increase their surface area. This increases air resistance, meaning the upward force becomes stronger at lower speeds. As a result, terminal velocity is lower, and the skydiver falls more slowly. When a parachute opens, this effect becomes dramatic. The parachute massively increases surface area and air resistance, creating a very large upward force. The new balance between gravity and air resistance occurs at a much lower speed, allowing the skydiver to descend safely to the ground. This video explains how terminal velocity is not about stopping motion, but about reaching a state where forces balance and acceleration ends. By understanding gravity, air resistance, and balanced forces, you’ll see why falling objects behave the way they do—and why skydiving can be both thrilling and safe when physics is on your side. Perfect for students, science enthusiasts, and anyone curious about how forces and motion work in the real world.