Question

If you leave the radius of a planet the same but double its mass, how does the gravitational pull of the planet on a person (equivalent to the person's weight) change? If you leave the mass the same, but double the radius how does the gravitational pull of the planet change?

thanks

Answer 1

Force=GMe*m/re^2

double M, double F
double re, F is 1/4 original

Answer 2

huh? we haven't learned any of these formulas..

Answer 3

SInce gravity gets weaker with distance, if you doubled the radius wouldn't you feel your weight less and less?

Answer 4

F = G*(M*m/r^2)

he's just saying that (according to a formula you've maybe never seen)

if you double the planet's mass (M in the formula) you will double the force due to gravity, because the relationship is linear

if you double the planet's radius, you will reduce the force due to gravity by a factor of 4, because r^2 is in the denominator