the acceleration of free fall of a satellite has a finite value so that an object at this position certainly has weight. making reference to the perception of weight by an observer, explain how astronauts inside this satellite arppear to be weightless. i thought weightlessness was when the gravitational force on a body from two masses 'canceled out' so there was no overall force acting of the body, but dont think this is true in this situation. can anyone explain this to me? also, find an expression in terms of Xo (amplitude) for the displacement of a particle when its velocity is half its maximum velocity. i have wXo/2 (w is angular velocity), however i dont know if 'w' should be in the expression if it says in terms of 'Xo'. can anyone suggest another expression? thanks in advance for your help.