How fast can you FALL?

A good way to find out how gravity works is jumping off a plane. Gravity's effect is present all the time, but, usually, you are standing on something solid, which counteracts. But what happens when nothing opposes to your fall?

Forces cause acceleration. When you jump off a plane, gravity pulls you down with the same acceleration that a McLaren F1 can do, one of the fastest cars in the world. You reach 100 km/h in just 3 seconds. But while falling, the acceleration is not constant. As your speed grows, the friction with the air becomes stronger, until you start feeling the air as a hurricane. After 10 seconds the air's resistance force equals gravity's effects and that's when your acceleration becomes zero. You have reached the speed limit.

Even though gravity seems impressive, it is, in fact, the weakest force in the Universe. Bodies attract themselves using gravity, but it is so small that you can't notice it. A huge amount of matter is required in order to have a perceptible gravity.

What is your speed limit?
The speed limit depends on the body's shape and weight. Light, fluffy things, such as a feather, drag so much air, that their speed limit is null, making them float. Rain drops can reach 27 km/h when falling, about a human's running speed. The fastest speed which a cat can fall with is 100 km/h, half of a human's, allowing the cat to survive, even from falling off a sky-scraper.

Can you fall faster?
Parachutists can increase or decrease their speed by modifying their body's position. Usually, a parachutist spreads its hands and feet to obtain air resistance and to control the fall. In this position, called "opened", the speed limit is around 200 km/h, and the parachute can be opened with absolutely no problems. To increase the speed, the parachutist stays vertically, with his hands and feet tight to the body. This way, he can reach 300 km/h.

How does a parachute work?
The functioning of the parachute is based on the air's resistance force. Right after opening up the parachute, the rapid increase of the air resistance creates as effect a violent breaking to the parachutist. It's falling speed reduces to about 20 km/h. If we had no air, the parachutist would fall accelerated and would hit the ground with over 1000 km/h!

The highest fall
The fall with a parachute from the biggest height happened in august 1960, when american pilot Joseph Kittinger jumped from a helium balloon from 31330 meters, meaning 3.5 times higher than the Everest! Air is rare at those heights and so, it creates less resistance. That's why Kittinger reached a top speed of 989 km/h (faster than a bullet) becoming the fastest man on Earth.