How does an astronaut float in a space shuttle ?

Explanation

(i) in space , the only force that acts on a spacecraft is the gravitational force of the earth . Therefore , the spacecraft is in a state of free fall.
(ii) The velocity in free fall is independent of the properties of an object and thus is the same for the spacecraft, the travellers and the objects in the space craft.
(iii) The free fall leads to weightlessness of space travellers as well as object in the spacecraft.
Being weightless, space travellers as well as objects in the spacecraft appear to be floating .