Force between two protons?

Question

Two protons are separated by a distance of 1.0×10−10 m (roughly the diameter of an atom).

(a) Calculate the electric force and gravitational force on one proton due to the other proton. The electric force is much larger. What is the ratio of the electric force to the gravitational force?

I'm so lost on this one. Do I use theory of universal gravitation ?

Answer 1

1)Electric force

F = k*(q1)*(q2) \ d^2

As F is electric force

k is coulomb's constant = 9*10^9 Nm^2\C^2

(q1) and (q2) are the charges of the 2 protons = 1.6*10^ -19 C

d is the distance between them

F= (9*10^9)*(1.6*10^ -19)*(1.6*10^ -19)\(1.0×10^ −10)^2

F= 2.304*10^ -28 \ (1.0×10^ −20) =2.304*10^ -8 N  

2)Gravitational force

F= G*(m1)*(m2) \ d^2

As F is Gravitational force

G is universal gravitational constant = 6.67*10^ -11 Nm^2\kg^2

(m1) and (m2) are the masses of the 2 protons = 1.67*10^ -27 Kg

d is the distance between them

F=(6.67*10^ -11)*(1.67*10^ -27)*(1.67*10^ -27)\(1.0×10^ −10)^2

F= 1.86*10^ -44 N

3)The ratio of the electric force to the gravitational force =  

(2.304*10^ -8) \ (1.86*10^ -44 ) =1.239*10^36 with no unit as it a ratio

That means that electric force = gravitational force multiplied by 1.239*10^36

Note

* is instead of multiply sign

^ is instead of power

Answer 2

Both the law of gravitation and Coulomb's Law have exactly the same form and result in a net force measured in Newtons:

F(g) = (G m1 m2) / r²

F(e) = (k q1 q2) / r²

G = 6.67 * 10^(-11) N m² / kg²

m(p) = 1.67 * 10^(-27) kg

k = 9.00 * 10^9 N m² / C²

q(e) = -1.602 * 10^(-19) C

Plug these in and you get the ratio.