Question

To simulate the apparent weightlessness of space orbit, astronauts are trained in the hold of a cargo aircraft that is accelerating downward at g. Why do they appear to be weightless, as measured by standing on a bathroom scale, in this accelerated frame of reference? Is there any difference between their apparent weightlessness in orbit and in the aircraft?

a) Due to the absence of gravitational forces in the aircraft.
b) Because the scale measures only the normal force, which is reduced in the accelerating frame.
c) The aircraft creates a vacuum, eliminating gravitational effects.
d) Their weightlessness is solely psychological in the aircraft.

Answer 1

Astronauts appear weightless in a falling aircraft because they are in free-fall, experiencing no additional forces. The apparent weightlessness differs from orbit where they continuously free-fall around Earth, creating sustained weightlessness.

Step-by-step explanation:

To simulate the apparent weightlessness of space orbit, astronauts are trained in the hold of a cargo aircraft that is accelerating downward at g, the acceleration due to gravity. The reason they appear to be weightless when standing on a bathroom scale is that in this accelerated frame of reference, both they and the scale are falling at the same rate. Thus, there is no normal force exerted by the scale on the astronauts, leading to a zero reading on the scale.

There is an important distinction between the apparent weightlessness experienced in the aircraft and in orbit. In the aircraft, the effect lasts only for the short duration of the parabolic flight path of the plane. In contrast, when in orbit, astronauts are continuously in a state of free-fall around the Earth, which means they experience a sustained period of weightlessness due to their spacecraft falling at the same rate as they are, hence they don't experience additional forces other than gravity, which is already accounted for by their orbital motion.