Question

Sally has a mass of 45.9 kilograms. Earth has a mass of 5.98 x 10^24 kilograms and an average radius of 6.38 x 10^6 meters.What is the force due to gravity between Sally and Earth? Include units in your answer. Answer must be in 3 significant digits.

Answer 1

Newton's law of universal Gravity:

F = G * (M1 * M2)/ r^2

Where:

G = gravitational constant = 6.674 x10^-11 Nm^2kg^2

M1 = mass 1 = 45.9 kg

M2 = mass 2 = 5.98 x 10 ^24 kg

r = Distance between the 2 objects = 6.38 x 10 ^6 m

Replacing;

$F=6.674x10^{-11}Nm^2kg^2\cdot\frac{45.9\operatorname{kg}\cdot5.98x10^{24}\operatorname{kg}}{(6.38x10^6m)^2}$

F = 450.048 N