An astronaut in low Earth orbit moves in (approximately) a big circle extending around the Earth. ... That can be interpreted as stating that in the astronaut's frame of reference, all bodies are subject to two forces, gravity and the centrifugal force, and the two are in perfect balance, adding up to zero. ... Wheel-shaped space . ... The science-fiction film "2001: A Space Odyssey" featured spinning space station, whose rotation provided the crew with "artificial gravity." ...

... 23a. The Centrifugal Force . ... 24a.The Rotating Earth . ... Sunlight Earth . ... One important rotating frame is the surface of the Earth, rotating with a period of about 24 hours--more accurately, 23 hrs 56.07 min or 86164 seconds. ... To derive the centrifugal acceleration on the equator (i.e. the force in Newtons on one gram mass, rotating with the Earth), we calculate in meters and seconds . ... Effective gravity on the equator is reduced by the rotation, but only by about 1/3 of a percent . ...

... How much brighter is the Sun as viewed from the planet Mercury as compared to Earth ? ... Actually, all of these questions can be answered through a very simple mathematical relationship known as the inverse square law. ... As the distance from the Sun increases the surface area of the sphere grows by the square of the distance. ... Common sense tells us that the Sun will be brighter and the inverse square law tells us how much brighter. ... gr = 0.912 G or 91.2% gravity felt at Earth's surface. ...