Causes of Weightness

Weightlessness is simply a sensation experienced by an individual when there are no external objects
touching one's body and exerting a push or pull upon it. Weightless sensations exist when all contact
forces are removed. These sensations are common to any situation in which you are momentarily (or
perpetually) in a state of free fall. When in free fall, the only force acting upon your body is the force of
gravity - a non-contact force. Since the force of gravity cannot be felt without any other opposing forces,
you would have no sensation of it. You would feel weightless when in a state of free fall.
These feelings of weightlessness are common at amusement parks for riders of roller coasters and other
rides in which riders are momentarily airborne and lifted out of their seats. Suppose that you were lifted
in your chair to the top of a very high tower and then your chair
was suddenly dropped. As you and your chair fall towards the
ground, you both accelerate at the same rate - g . Since the chair
is unstable, falling at the same rate as you, it is unable to push
upon you. Normal forces only result from contact with stable,
supporting surfaces. The force of gravity is the only force acting
upon your body. There are no external objects touching your
body and exerting a force. As such, you would experience a
weightless sensation. You would weigh as much as you always
do (or as little) yet you would not have any sensation of this
weight.
Weightlessness is only a sensation; it is not a reality
corresponding to an individual who has lost weight. As you are
free falling on a roller coaster ride (or other amusement park
ride), you have not momentarily lost your weight. Weightlessness has very little to do with weight and
mostly to do with the presence or absence of contact forces. If by "weight" we are referring to the force
of gravitational attraction to the Earth, a free-falling person has not "lost their weight;" they are still
experiencing the Earth's gravitational attraction. Unfortunately, the confusion of a person's actual weight
with one's feeling of weight is the source of many misconceptions.