In designing rotating space stations to provide forartificial-gravity environments, one of the constraints that mustbe considered is motion sickness. Studies have shown that thenegative effects of motion sickness begin to appear when the rotational motion is faster than approximately 2.25 revolutions per minute. On the other hand,the magnitude of the centripetal acceleration at the astronauts'feet should equal the magnitude of the acceleration due to gravityon earth. Thus, to eliminate the difficulties with motion sickness,designers must choose the distance between the astronaut's feet andthe axis about which the space station rotates to be greater than acertain minimum value. What is this minimum value?