Microgravity Contributed by Greg L. Vogt
Crew Educational Affairs Liaison, NASA Johnson Space Center Gravity is an attractive force that is a fundamental property of all matter. Whether an object is a planet, a feather or a person, each exerts a gravitational force on all other objects around it. Physicists identify gravity as one of the four types of forces in the universe (the others are strong and weak nuclear forces and electromagnetic force). The strength of the attraction between two objects is directly proportional to the product of the masses of those objects and inversely proportional to the square of the distance between the centers of mass of those objects: in other words, the larger the objects the stronger the attraction between them and the greater the distance between the objects the weaker the attraction. When measured at the surface of the Earth, the acceleration of an object acted upon only by Earth’s gravity is commonly referred to as "1 g" or "unit gravity." This acceleration is approximately 9.8 meters per second squared (m/s2). On Earth, gravitational force is important in providing orientation and guidance to many forms of life including plants. For example, plants orient themselves with gravity so that shoots grow up and roots grow down and water and nutrients are transported through the plants against the pull of gravity. | |
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