Question

If you weigh 690n 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 19.0 km ?]

Answer 1

-- If you weigh 690N on the Earth, then your mass is about

(690N) / (9.8 m/s²) = 70 kg .

-- If your mass is 70 kg then your weight on that neutron star would be

G M₁ M₂ / R²

= (6.67 x 10⁻¹¹ N m²/kg²) (70 kg) (1.989 x 10³⁰ kg) / (19,000 m)²

= (6.67 x 10⁻¹¹ x 70 x 1.989 x 10³⁰) / (3.61 x 10⁸) N

= (6.67 x 70 x 1.989 x 10¹⁹) / (3.61 x 10⁸) N

= 2.57 x 10¹³ Newtons .

(about 2,890,000,000 tons !)