Parachute

How do parachutes work?
Parachutes work using air resistance. It slows down the speed at which an object is falling at. If you fall from a plane without a parachute, your relatively compact body zooms through the air like a stone; open your parachute and you create more air resistance, drifting to the ground more slowly and safely—much more like a feather. Simply speaking, then, a parachute works by increasing your air resistance as you fall.

Why do parachutes have a hole at the top?
It is to allow a smooth airflow through the parachute. Without it, the trapped air would escape from the sides of the parachute, causing it to swing back and forth dangerously.

What is terminal velocity?
Terminal velocity is when the force of air resistance is equivalent to the gravitational force, therefore there is no net acceleration. The object would descend at a steady speed.

How to calculate terminal velocity?
Terminal velocity formula: v = the square root of ((2*m*g)/(ρ*A*C))

• m = mass of the falling object
• g = the acceleration due to gravity. On Earth this is approximately 9.8 meters per second per second.
• ρ = the density of the fluid the object is falling through.
• A = the projected area of the object. This means the area of the object if you projected it onto a plane that was perpendicular to the direction the object is moving.
• C = the drag coefficient. This number depends on the shape of the object. The more streamlined the shape, the lower the coefficient. 

What are some uses for parachutes?
The uses of parachutes include sports such as skydiving and parasailing, military (to drop soldiers and equipment onto the battlefields. Some airplanes also use parachutes, they are used to protect the airplanes from serious damage during crashes.