Question

the weight of the body on the earth is 392 Newton what will be the weight of this body on another planet whose mass is double of the earth

Answer 1

Let the mass of the body on the surface of Earth = m  kg
weight of the body on Earth = m * g  = G M m / R²
         g = 9.8 m/sec²  on Earth
         g = acceleration due to gravity = G M / R²

     The weight of a body on a planet is directly proportional to Mass of the planet and inversely proportional to square of radius of the planet.

   weight =  392 * 2 / (4)²  Newtons = 98 Newtons

Answer 2

Soln:- The 'g' of the earth is 9.81 m/s-2=10m/s-2

Mass=392/10
=39.2 kg

On other planet whose mass is doubles of the earth ,
g=10×2=20ms-2


Weight=mg
=39.2×20kgms-2
=784 N