Jim, Here are several corrections of your statements. See below.
---- Original message ---- >Date: Sun, 25 Jan 2009 18:38:55 -0600 >From: James Frysinger <[email protected]> >Subject: [USMA:42574] Re: The real physics (was Small item seen on TV) >To: "U.S. Metric Association" <[email protected]> >... > >The astronauts orbiting the Earth are not weightless. False. There weights are nearly zero with respect to their immediate surroundings. They are "weightless" in first approximation in the reference frame of their spacecraft. > Their gravitational weight is the centripetal force that pulls them around in > orbit. False. The central force accelerates them toward the center of the earth, but it is perpendicular to their direction of motion in the orbit. > Likewise, their orbiter's weight pulls it around in orbit. False. There is no tangential pull (thrust) and little drag on the spacecraft in parking orbit. >... *With the earth as the frame of reference*: >The weight of an object at Shuttle Orbiter altitudes is >roughly 92 % of its >weight on the surface of the Earth. At >ISS altitudes it's roughly 91 %. *With the orbiter as the frame of reference*: >...the astronauts are in orbit with their orbiter and since >both experience >the same centripetal acceleration, the >astronauts feel "weightless" and float >around inside the >orbiter. > >A similar phenomenon can be experienced (briefly) in an >elevator whose cable >has been cut... I have no quibble with your elevator and other examples. Gene.
