You could always directly use F = G M m / r², but that takes forever.
<span>It is best to know that, on Earth's surface, the astronaut would weigh </span> <span>F = m g = 579.2 N </span> <span>where m = 59.1 kg and g = 9.8 m/s². </span>
<span>You then notice from F = G M m / r² that doubling the mass of the earth would double his weight and doubling the radius would give 1/4 his original weight. So... </span> <span>F = 1/4 * 2 * 579.2 N = 290 N </span>
