Why do astronauts feel “weightless” in space?

Question

anonymous · Answer

Because centrifugal  and gravitational forces act in directions opposite to each other, and their magnitudes are equal, so the net force acting on an object is zero. This applies when we talk about astronauts orbiting around the earth. 
I hope you know what centrifugal force is? When the object moves in a  circle it feels pull which is action of centrifugal force, if no force counterbalances it, the object will continue its way in a straight line or in other words it will fly (move) away.

unklerhaukus · Answer

there is no ground pushing up

anonymous · Answer

The feeling of weightlessness is due to astronauts free falling.  On earth there is a force that acts downwards on us called called gravity and another force that pushes upwards called inertia, in space there is nothing pushing upwards on us (technically there is a force but it is extremely small) that is what causes us to feel weightless

vincent-lyon.fr · Answer

Because they are in free fall and so is their spacecraft. Watch: http://www.youtube.com/watch?v=iQOHRKKNNLQ&feature=g-all-u According to proper definition of weight, they do not "feel" weightless, they ARE weightless. Weight relative to a reference frame is the (vector) sum of gravitational pull and inertial forces due to the motion of the reference frame.

anonymous · Answer

no gravity|dw:1337995706870:dw|

anonymous · Answer

@Itsjena
Wrong, the gravity is there, and everywhere in Universe.

vincent-lyon.fr · Answer

@itsjena ArchiePhysics is right, the word 'zero-gravity' is misleading and should be re-thinked. Watch the YouTube contribution by 1Veritasium: http://www.youtube.com/watch?v=iQOHRKKNNLQ&feature=g-all-u

anonymous · Answer

because of lack of gravity

vincent-lyon.fr · Answer

@lele41 Please watch the YouTube video mentioned above.
Gravity is almost as strong in a space station in orbit as on the surface of the Earth.

anonymous · Answer

centrifugal force is not actually a force, it can only be used as force relatively, it is an inertial effect that does not apply any force at all, it is "fictitious", the object is not being pulled outward but the object is rotating outwards in a straightline tangent to the orbit.