Question

The table lists the values of the electrical force and the gravitational force between two protons.

Answer 1

The electrical force between two protons is given by:
$F_e = k \frac{e^2}{r^2}$
where
$k=8.99 \cdot 10^9 Nm^2C^{-2}$ is the Coulomb's constant
$e=1.6 \cdot 10^{-19}C$ is the proton charge
r is the separation between the two protons

The gravitational force between the two protons is given by:
$F_g=G \frac{m^2}{r^2}$
where
$G=6.67 \cdot 10^{-11} m^3 kg^{-1} s^{-2}$ is the gravitational constant
$m=1.67 \cdot 10^{-27} kg$ is the proton mass
r is the separation between the two protons

If we divide the electric force by the gravitational force, we get
$\frac{F_e}{F_g}= \frac{k}{G} \frac{e^2}{m^2}=1.2 \cdot 10^{36}$

which means that the electric force between the two protons is $1.2 \cdot 10^{36}$ times greater than the gravitational force.

Moreover, the two protons have same electric charge, and the electrostatic force between two same-sign charges is repulsive, while the gravitational force is always attractive: therefore, the correct answer is
The electrical force is 1.2 × 1036 times greater than the gravitational force, but only the gravitational force is attractive.

Answer 2

The electrical force is 1.2 × 1036 times greater than the gravitational force, but only the gravitational force is attractive.