Is there a unified equation for the forces of gravity and electromagnetism?

[Einstein's Cat]

Is there an equation which combines Newton's equation of calculating the gravitational force between two masses with that of Coulomb's equation of describing the electromagnetic force between two particles? In other words, does an equation exist which describes the relationship between mass and electromagnetism as opposed to the charge of the masses and the electromagnetic force between them? Thank you and if I'm simply being ignorant please say!

 

[Orodruin]

There is currently no accepted theory in which the mass and charge are related. They are independent quantities.