Determine what the mass of a pair of protons would be if the

Determine what the mass of a pair of protons would be if the gravitational and electrical forces between them were equal in magnitude.

Solution

suppose of mass of proton is m.

and known charge on proton is 1.6 x 10^-19 C.

so Gravitational force = electrical force

G * m * m / d^2 = k * q * q / d^2

(6.67 x 10^-11 x m^2 ) = (9 x 10^9 x (1.6 x 10^-19)^2)

m = 1.86 x 10^-9 kg