# Weight on a neutron star ( universal gravity)

1. Mar 10, 2009

### tnutty

1. The problem statement, all variables and given/known data

Neutron stars, such as the one at the center of the Crab Nebula, have about the same mass as our sun but a much smaller diameter.

If you weigh 650 N on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter of 15.0 km ?

Take the mass of the sun to be = 1.99×1030 kg , the gravitational constant to be
G = 6.67×10−11 , and the acceleration due to gravity at the earth's surface to be
g = 9.810 .

Express your weight W_star in newtons.

2. Relevant equations

F = GMm/r^2

3. The attempt at a solution

mg = w
mg = 650
m = 650/g = 650 / 9.810 = mass of you

F = GMm/r^2

ma = GMm/r^2

a = GM/r^2 = acceleration in the neutron star.

F = ma;

= Mass of you * acceleration in neutron star

where

acceleration in neutron star =

[ 6.67 * 10^-11 * 1.99 * 10^30 ] / r^2--(or D/2)^2

=

6.67 * 10^-11 * 1.99*10^30 / 7500^2
~ 3.527 x 10^12

so

w = mg
= 650/9.81 * (3.527 * 10^12)

is this right, can you check my calculation?

2. Mar 10, 2009

### tnutty

I got it, thanks fooorrrr alll yoouuuurrrrr heeeellllppppp guuuuuuyyyysss
(cough*sarcasm*cough).