Would you jump out of a plane if someone paid you? Would you pay to jump out of a plane? Thrill-seekers enjoy skydiving and often pay several hundred dollars to hurl towards the ground at high speeds. How do they survive the jumps? With the power of physics!
Gravity, Drag, and a Good Parachute
When you jump out of an airplane, gravity pulls you toward the ground. Your speed increases at a rate of 9.8 meters per second, every second. In a world without air, you could figure out how fast you were going at any point during your fall by multiplying
Fortunately, skydivers have another force on their side: air resistance. The faster they're falling, the harder it becomes to move past the air particles that surround them. Eventually, the force of air resistance (also known as drag) becomes the same as the force of gravity. When this happens, skydivers stop speeding up and are said to have reached terminal velocity. When they open their parachutes, it becomes even harder to move through the air. The drag force on their parachutes slows skydivers down sufficiently for them to hit the ground at relatively slow speeds.
Some skydivers attempt incredible stunts. In October 2012, Austrian daredevil Felix Baumgartner jumped from over 120,000 feet above the Earth and landed safely. In May of the same year, British skydiver Gary Connery jumped from 2,400 feet in the air. He landed safely without ever deploying a parachute.
See for yourself: http://www.wired.com/wiredscience/2012/05/skydiving-without-a-parachute/
At the links below, watch Felix Baumgartner's 24-mile jump and learn more about the physics and math behind skydiving.