Physics of Skydiving

The Physics of Skydiving

What Is Skydiving?

Skydiving is an adrenaline-based sport with a fairly simple concept -- jump from a high place (usually out of a plane) from several thousand feet above sea level and hope and pray for a safe landing. This safe landing is often times achieved through the use of a device called a parachute, which enables the skydiver to reduce his speed to such a point that colliding with the earth will not be fatal.

This paper will explain a few of the key concepts behind the physics of skydiving. First we will explore why a skydiver accelerates after he leaps out of the plane before his jump, second we will try and explain the drag forces effecting the skydiver, and lastly we will attempt to explain how terminal velocity works.

Acceleration Due To Gravity

Why does a skydiver accelerate as he leaps from the plane? The answer to this question is relatively simple: gravity. Gravity acts on all bodies in the universe, and each bodies' gravitional effects are related. The body that the majority of the human population is affected by is the planet earth. The gravitational acceleration produced from earth is approximately 9.8 m/s^2, which changes slightly as you move closer to or away from the earth's center of mass.

Lets examine an instance for which a person named Joe prepairs for his first skydiving experience. Joe gets on a plane with an instructor and heads towards the sky.

First off, while Joe is in the plane, he does not constantly accelerate downward, assuming the altitude of the plane remains constant. Why might this be the case? Newton's Second Law states, "The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass" ...

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...e equals mass times acceleration, and mass is constant, acceleration must then be equal to 0. Thus velocity has reached its max and is now constant.

Here is an example of how air resistance affects two different bodies.

Interestingly enough, one can actually change their "terminal" velocity. For instance, if Joe were to jump out of the plane and position in the prone, spread eagle position, his surface area would be at his maximum. Thus the terminal velocity he would reach would be lower than the terminal velocity he would reach if he dove from the plane head first. When Joe transitions from spread eagle to the head first position, his surface area decreases, thus allowing for an increase in speed.

With the knowledge of these concepts of physics, one should now be able (with training) to safely partake in skydiving. A safe landing should not be an issue!