Apparent weightlessness in Orbit? (1 Viewer)

[StGeorgeDragons]

When a space crew is in orbit around the earth, are they in apparent weightlessess in their ship?
They are not in free fall, and are still under the influence of the earths gravity, so it would not seem so....

 

[xiao1985]

When a space crew is in orbit around the earth, are they in apparent weightlessess in their ship?
They are not in free fall, and are still under the influence of the earths gravity, so it would not seem so....

they are in orbit, hence constantly feeling the centripetal acceleration (gravity in this case)... and sicne the space ship too is undergoing centripetal acceleration at the same rate, hence it is free falling...

 

[Will Hunting]

are they in apparent weightlessess in their ship?

Sure are. The spacecraft is in uniform circular motion about the Earth, meaning that the centripetal force of the orbit is in harmony with the gravitational force of attraction between Earth and spacecraft. Now, since net forces on the spacecraft are zero (atmospheric friction, if any, is overcome by thrust), the crew experience a zero g load and, therefore, apparent weightlessness. Also, in order to bring this system's forces into harmony, an orbital velocity related to the altitude of the spacecraft and the radius and mass of the Earth must be achieved and maintained by the spacecraft:

Fc = Fg
mv^2/r = GmmE/r^2
v^2 = GmE/r
v = sqrt(GmE/r)

So, you're correct in saying that the crew are not in free fall, however, if you think about it, the conditions make the orbit of a spacecraft analogous to a free fall scenario anyway, meaning that the crew are, in effect, experiencing the same feeling as they would falling straight down under the influence of gravity.