Why do astronauts experience weightlessness?

Let W be the weight of the astronaut, and R be the reaction or contact force with anything say Chair, Belt etc...
And let the Space vehicle move with acceleration 'g'.
Then,
We have W+R=(W/g)*g
which gives R=0 ie the net contact force on the astronaut is zero.
With no reaction to the force of gravity exerted onn the body, there is indeed no sensation of weight.