Answer:
40 cm
Explanation:
The focus of a spherical convex mirror is the point at which the rays of an object converge in the infinite, it is also the point at which an object must be placed so that its image is formed in the infinite. The distance from the focus to the origin is called the focal length and is called f. It is related to the radius of the mirror, R, according to:

rewriting for R:
.
To be honest I’m not sure you might want to ask Newton as he’s an expert best of luck
the axis acts against and it would be a contact force
no BECQUSE POSUM BROOB SHSHSJ