Question

If the mean distance of a planet from sun is 4 times the mean distance of earth from sun, then how many years does that planet take to move once around the sun?

Answer 1

Answer:

8 years

Explanation:

Let the distance between the earth and the sun be  R.

Thus distance between the planet and the sun       R′=4R

Time taken by earth to orbit the sun    T=1 earth year

Using Kepler's 3rd law,         T2∝R3

⟹    TT′=(RR′)1.5

∴    1T′=(R4R)1.5=41.5                   ⟹T′=8 Earth years

HOPE IT MAY HELP U