The definition of a fulcrum is a pivot point around which a lever turns, or something that plays a central role in or is in the center of a situation or activity. 1  A pivot point around which a lever turns is an example of a fulcrum. 2  A person around whom all activity revolves is an example of the fulcrum.
Weightlessness, condition experienced while in free-fall, in which the effect of gravity is canceled by the inertial (e.g., centrifugal) force resulting from orbital flight. The term zero gravity is often used to describe such a condition. Excluding spaceflight, true weightlessness can be experienced only briefly, as in an airplane following a ballistic (i.e., parabolic) path. Crews of spacecraft are subject to the problems of weightlessness. It was learned from early Soviet and U.S. manned missions that there is a reduction in heart and respiration rates and a progressive loss of body weight and bone calcium during flights of relatively short duration.
Weightlessness. 1  People rarely get to experience firsthand the phenomenon of weightlessness, but that doesnât keep SAT II Physics from testing you on it. There is a popular misconception that astronauts in satellites experience weightlessness because they are beyond the reach of the Earthâs gravitational pull. If you already know this isnât the case, youâre in a good position to answer correctly anything SAT II Physics may ask about weightlessness.