What is the semimajor axis (in au) of a planet with an orbital period of 14 years?

5.808 AU

Explanation:

According to Kepler’s Third Law of Planetary motion “The square of the orbital period of a planet is proportional to the cube of the semi-major axis (size) of its orbit”.  

(1)

Talking in general, this law states a relation between the orbital period of a body (moon, planet, satellite, comet) orbiting a greater body in space with the size of its orbit.  

However, if is measured in years, and is measured in astronomical units (equivalent to the distance between the Sun and the Earth: ), equation (1) becomes:

(2)

Knowing and isolating from (2):

(3)

(4)

Finally:

report!

explanation:

physics means: "the branch of science concerned with the nature and properties of matter and energy. the subject matter of physics, distinguished from that of chemistry and biology, includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."