Why do they say centrifugal Force in space is fictitious,When in a centrifuge we experience a real force?

Answer 1

The Cetrifugal force is a fictitious force not because it isn't real, but because the source of the force is not what it appears to be from the person experiencing it.

In an inertial reference frame, any motion the reference frame itself is undergoing cannot be detected by measurements conducted entirely within the reference frame. For example, we cannot detect the motion or rotation of the Earth simply by examining the Earth itself. We have to look away from the Earth to notice it. When the reference frame itself becomes non-inertial- meaning an external force acts upon it- that force will be experienced inside the reference frame but it would appear to examinations inside the frame to be some kind of imaginary force. For example, when you are in a roller coaster and as it speeds down a drop, it reaches the bottom and begins moving up another hill. When moving up, you feel forced down into the car. There really is no force pushing you down into the car, it's the car's acceleration as it moves upward that causes this sensation. However if you could only see the car and yourself and not the track, it would appear to you that there was some kind of force pushing you down into the car. This is an imaginary force. The centrifugal force is such a force.