Newton developed a "thought experiment" to demonstrate this concept. Imagine placing a cannon at the top of a very tall mountain. Once fired, a cannonball falls to the Earth. The greater the speed, the farther it will travel before landing. If fired with the proper speed, the cannonball would achieve a state of continuous free-fall which we call orbit. The same principle applies to the Space Shuttle or Space Station. While objects inside them appear to be floating and motionless, they are actually traveling at the same orbital speed as their spacecraft: 17,500 miles per hour (28,000 km per hour)! Objects in a state of free-fall or orbit are said to be "weightless." The object's mass is the same, but it would register "0" on a scale. Weight varies depending on if you are on the Earth, the Moon, or in orbit. But your mass stays the same, unless you go on a diet!
NASA has a Reduced Gravity Aircraft based at the Lyndon B. Johnson Space Centre. It is an airplane called the “Vomit Comet” that flies in a parabolic arc that is approximately 10 kilometres long. The airplane first climbs in altitude and then falls in such a way that the flight path corresponds to that of an object in free fall. The people inside are temporarily weightless for a time period of 25 seconds. Typically one flight lasts two hours in which 40 parabolas are flown.
NASA has a Reduced Gravity Aircraft based at the Lyndon B. Johnson Space Centre. It is an airplane called the “Vomit Comet” that flies in a parabolic arc that is approximately 10 kilometres long. The airplane first climbs in altitude and then falls in such a way that the flight path corresponds to that of an object in free fall. The people inside are temporarily weightless for a time period of 25 seconds. Typically one flight lasts two hours in which 40 parabolas are flown.
![Kepler’s Laws ,[object Object],Topic 2.1 – Exploration of Space](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)