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Why the mass of Jupiter is 319 times greater than that of the earth but g is only 2.5 times bigger than that of the earth?

We all know that, ∝ 1/R2

From this, we conclude g is inversely proportional to the square of the radius of any heavenly body. If the radius increases, the 'g' will decrease.

Though the mass of Jupiter is very high, its volume is also very high that results in a higher radius. So, the 'g' of Jupiter gets its value decreased. Hence, the mass of Jupiter is significantly high than that of the earth but the 'g' varies a little only.