The mass of the earth is `6 xx 10^(24) kg`. The constant of gravitation `G = 6.67 xx 10^(-11) "N-m"^(-2) kg^(-2)`. The potential energy of the earth and moon system is `-7.79 xx 10^(28) J`. Determine the mean distance between earth and moon.

Explanation

Potential energy of the earth and moon system is
`U=(-GMm)/(r)`
`rArr r=(-GMm)/(U)=(-6.67xx10^(-11)xx6xx10^(24)xx7.4xx10^(22))/(-7.79xx10^(28))`
`rArr r = 3.8 xx 10^(8)`m