Flying Changes our Mind and Body

A plane throws the air down behind it by making a spinning vortex - a kind of mini-tornado.

Most of the vortex is moving downward, but not all. There's a huge draft of air moving down in the center, but the air also swirls upward on either side of the wingtips, reducing lift.

If you're in a plane and steering around a circle, the centripetal force comes from leaning into a curve, just like a cyclist leans into a bend.

Steering involves banking, where the plane tilts to one side causing the one wing to dip. The plane's overall lift is tilted at an angle, making some of the lift act sideways. This sideways part of the lift provides the centripetal force that makes the plane go around in a circle. But turning the plane in a circle will make it lose lift and altitude, unless the pilot uses the elevators to increase the angle of attack to cause lift again.

The thrust required for an object to overcome Earth’s gravity and atmospheric resistance and move towards space is called escape velocity. Besides Earth, the gravitational forces that can affect the object are those coming from the sun, moon and even other planets.

Apart from space vehicles and the military, rockets are used in life-saving rescue flares and fireworks, and even the ejector seats in military planes.

• One of the earliest devices that used rocket propulsion was called the aeolipile, designed in the 1st century AD by Heron of Alexandria, and used steam to spin a metal ball.
• Early prototypes of rockets were produced for firework displays in China in the 13th century, with the real, metal versions coming in the 19th century, used in Navy ships as an upgraded version of cannon.
• Early rockets use flammable substances like gunpowder that propel it using the thrust of exhaust gases.