Question

Why is centrifugal force a pseudo force?

Answer 1

a force, arising from the body's inertia, which appears to act on a body moving in a circular path and is directed away from the centre around which the body A fictitious force, also called a pseudo force is an apparent force that acts on all masses whose motion is described using a non-inertial frame of reference, such as a rotating reference frame.

Answer 2

Centrifugal force is a pseudo force because it acts only in a non inertial frame of reference i.e. a frame which is accelerating with respect to the ground.
Centrifugal force exists only in a non inertial frame and centripetal force exists only in an inertial frame. Thus, centrifugal and centripetal force never exist together.