Question

a body has a weight w on surface of earth. what will be it's weight on a planet whose mass 15 times of earth and whose radius 4times of earth?? ​

Answer 1

By gravitation we know  F

Answer 2

let mass of the body be M and intensity of gravity be g

w=Mg

$g = \frac{Gm}{ {r}^{2} } \\ \\ m = mass \: of \: earth \\ \\ r = radius \: of \: earth \\ \\ now \: for \: some \: planet \: x \: {m}^{0} = 15m \\ \\ {r}^{0} = 4r \\ \\ then {g}^{o} = \frac{15}{16} \frac{Gm}{ {r}^{2} } \\ \\ {g}^{0} = \frac{15g}{16} \\ \\ now \: weight \: {w}^{0} = \frac{15}{16} Mg \\ \\ {w}^{0} = \frac{15}{16} w$

hope it helps.