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:
.
Atmosphere - gas
sea and oceans - liquid and solid
land -liquid and solid
living things and plants - liquid
Answer:
The strength of gravity decreases.
An example of that would be if you were in space; you float around because there's no gravity.
Explanation:
its hard to explain its very complex but its so they can function properly