Is this point of contact an inertial frame?

[Taufik]

Consider a disc being pulled by a constant force F and it is performing pure rolling. Now, the disc has a certain acceleration, point A has a acceleration in right direction and another centripetal acceleration in vertically upward direction but it has zero instantaneous velocity because of pure rolling. If I consider my frame of reference as point A, then it should be a non-inertial frame since it has acceleration but my physics teacher said that it is an inertial frame.
So, is point A an inertial or a non inertial frame?

If it a non inertial frame of reference, then what would be the torque equation in that frame about point A? Is the torque equation that I have written correct?

 

[Orodruin]

An inertial frame is a set of coordinates in which Newton's laws hold. There is no such thing as "a point being an inertial frame". For example, I can place the origin of a reference frame at the center of the disc. If the directions of the coordinate axes are fixed, that reference frame would be inertial, but if it rotates with the wheel, it would be a non-inertial frame.

Your teacher is likely referring to the frame where the origin is placed at the point of contact (not moving around the disc's perimeter), which would just be a translation away from the reference frame described by placing the origin at the center of mass and using fixed coordinate axes.

point A has a acceleration in right direction

No it doesn't. Considering the inertial frame with its origin in the disc's center, it is fairly obvious that the acceleration of point A is only in the upwards direction. Acceleration is invariant under changes of inertial frame.

 

[Andrew Mason]

Consider a disc being pulled by a constant force F and it is performing pure rolling. Now, the disc has a certain acceleration, point A has a acceleration in right direction and another centripetal acceleration in vertically upward direction but it has zero instantaneous velocity because of pure rolling. If I consider my frame of reference as point A, then it should be a non-inertial frame since it has acceleration but my physics teacher said that it is an inertial frame.
So, is point A an inertial or a non inertial frame?

Point A is undergoing acceleration even when it is in contact with the ground. Its motion in any arbitrarily small neighbourhood of the point of contact is not uniform.

AM