Katie and Mark sit next to one another in class. She has a mass of 40 kg and his mass is 65 kg. If they are 0.5 meters apart, what is the gravitational force between Mark and Katie?

A :-) for this question , we should apply
F = GMm by d^2
( For making the calculation easy , first remove the decimals )
Given : G = 6.7 x 10^-11 Nm^2 / kg^2
= 67 x 10^-12 Nm^2 / Kg^2
M = 65 kg
m = 40 kg
d = 0.5 m
Solution -
F = GMm by d^2
F = 67 x 10^-12 x 65 x 40 by 0.5 x 0.5
F = 4355 x 40 x 10^-12 by 0.25
F = 174200 x 10^-12 by 0.25
F = 696800 x 10^-12

.:. The Gravitational force between mark and Katie is 696800 x 10^-12

The earths atmosphere is made up of nitrogen and oxygensolids turning into gases is called sublimation.